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My 1910 Mitchell "parts car" project


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8 hours ago, alsfarms said:

I am studying my 9" South-bend with the idea that I would sure like to be able to fit collets in my headstock as you have done and use so frequently.  To remove error I use the four jaw chuck a lot and am good at dialing it in, however, it would be great to simply install a piece and start the machining process and know that it will stay much more repeatable.

 

I don't know too much about South Bend but I'm guessing that the fixtures to use collets are readily available. My only reservation would be that they are probably small collets.

 

[EDIT] The South Bend 9 used a 3C collet. I don't know what the largest size is but I suspect around 3/4". I tend to use the sizes from 3/4" to 1" most of the time - I don't think I've ever put those smaller than 1/4" in the machine and I may have used the 1/4" once in five years. I also don't think you can get square and hex versions - at least not as cheaply as 5C. What size is your big lathe?

Edited by JV Puleo (see edit history)
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I finally got to use the dividing head today although I had to stop and try to remember how to set it up. I've only used it 4 or 5 times.

Drilling the 18 holes.

 

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I reamed these holes 1/4" which leaves no room for a little play.

 

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Then I did the 20 holes and threaded them.

 

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It goes together but it is a tiny bit tight. I think I should enlarge the 1/4" holes a tiny bit so I'm leaving the setup alone and looking for a .255 reamer. I may have one so I'll have to ransack the reamer drawer before I order one.

 

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I found a .257 so I think I'll use that. It occurred to me that the hole size isn't as critical as I'd originally thought since both shafts will have to align perfectly in any case.

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The slightly oversize reamer made a world of difference. I tried it in 4 or 5 positions and it screwed together easily in all of them and the shaft in the center didn't bind at all. I don't often use the word "perfect" in regard to my own work but this comes as close as I've ever managed.

 

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So I cleaned the dividing head up and put it away. Ill leave the chuck on it as using collets with it has always been a "work around" to compensate for not having a chuck.

 

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Finishing that left me wondering what to do next. I am perilously close to having to dismantle the engine and start machining the crankcase... but first I played around with the mag, removing the half a coupling that was on it.

 

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This is a Bosch ZF4. Based on the serial number it was made in 1912 so it's well withing the range of years I'm working with. What I don't know is how it was wired since it pre-dates the introduction of the impulse starter and I don't know how you'd connect a battery - its something else I'll have to figure out. [Edit] In looking at the ZF4 manual it states it was intended for cars with a bore up to 80mm. I've never been able to get an informed opinion what the difference was between a mag like this and the next size larger. I actually have a bigger 4 cylinder mag (I think it's a D4) but it's actually too big to fit on the engine... I've come to the conclusion that looking for an answer on the internet just leaves me with more questions.

 

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Then, because I couldn't think of anything else, I decided to re-make the front bearing holder for the camshaft. The original has a Babbitt lining and is awfully heavy for what it does. I'm trying to save as much weight as possible, especially as I have increased the size of a few parts. Overall, with the aluminum rods and pistons, I think I will be reducing the weight of the engine by at least 30 lbs. - maybe more but every bit counts.

 

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(The original piece is in the foreground.)

Edited by JV Puleo (see edit history)
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I may have found a period answer to my magneto issues... except I don't know enough about electricity to sort it out. Here are two pages from a 1914 issue of Motor Age showing the wiring for a Bosch NU4 mag. The manual that came with the ZR4 - which is what I have - shows the same wiring diagram and specifically states that it can be wired with the "vibrating coil" for cars that do not have an electric starter. Everything is quite straight forward except I don't understand the coil. All the cols I'm familiar with have a third connection for the distributor so what is this one doing? Is it a big condenser? The magneto manual also says it works with either 6 or 12 volt systems.

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They might. The mag I'm thinking of using is a ZR4 and it was used mostly on marine engines and heavy duty stationary engines. apparently it was severely over built so non-automotive folks may well have a better idea how it worked. I did find a Popular Science article on making one - or what may be one - It's just a trembler coil with the secondary circuit short circuited. But, I'd like to get it right and I don't want to go down the road reliant on 100 year old electrical components so some modern, easily replaced part is very much needed.

 

jp

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Joe,

I might be able to help you. I am finding it difficult to read about the system on the copy you have posted. I have tried increasing the size, but that didn't help. Can you post a better copy?

Mike

 

PS: My guess is that the vibrating coil is acting similar to a 'trembler coil' like I have on the Crestmobile and that model T Fords have.

Edited by Mike Macartney
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Thanks guys. I'll send the original jpeg from home - right now I'm in the office.

If I can sort this out it simplifies quite a bit. The mag I have was introduced in 1911 and doesn't have the same connections as the Bosch DU series so it must have used this system for crank starting, since it also pre-dates the impulse starter. I think I have some Model T coils - new ones in the plastic cases, but they have been in a drawer in my basement for 30 years.

jp

Edited by JV Puleo (see edit history)
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I've found more... this appears to be a really good system that would make using a high tension magneto without an impulse coupling a breeze. I wonder why no one has ever pursued it. I know I've seen the switches for it... I've even had a couple and were the great Bills Auto Parts still around I could probably find one in a couple of hours. The parts were Bosch VD Ed. 1 and VD Ed. 2. I'll even bet there are some NOS examples out there but I've no idea where to look.

 

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After that big lump of aluminum bar was drilled and reamed to 1-1/4" I mounted it on a mandrel and turned the small end.

 

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This end fits into the crankcase. I made it about .004 undersize so it will slip in easily. The four mounting bolts should hold it secure and I can't be certain that the Mitchell-Lewis people actually bored the hole straight so a tiny amount of wiggle room is probably wanted.

 

I then pressed it off the mandrel and turned it around.

 

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And turned the other end. The housing that encloses the timing gears clamps around this. It's about .050 long because when I have the timing gears in hand I'll have to fit them and I'm thinking of shortening this about .070 to accommodate a thrust bearing.

 

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Then I set up the original piece in the dividing head to locate the holes. The dividing head is much easier to use in the drill press. A B&S dividing head has a 1"40 gear reduction so 10 thurns of the handle is 90 degrees.

 

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Then the holes were drilled and counterbored.

 

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And I realized that I've reached something of a milestone. This is the end of the parts I can make for the upper half of the engine (though some will have to be fitted later). It is now time to start on the crankcase so I started stripping it and putting the parts away.

 

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I continued stripping the engine down this morning and noticed something. This is the intake port that I thought I'd have to bore out. The scribed line was taken from the flange before the actual intake elbow was screwed in.

 

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But when I look at the inside diameter of the intake manifold it doesn't look as if I have the problem I'd thought.

 

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With the jugs removed I have to make plates to take their place. for lack of a better name I think of them as "torsion plates." The idea is to do all the crankcase machining with them bolted in place to replicate the stress the case isl under when the jugs are in place. These crankcases are a lot more flexible than you'd think and if you don't do this you run the risk of having the line boring not line up when the engine is assembled.

 

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I also worked on the water pump hold down. This casting was literally the first part I made, 7-1/2 years ago. I knew virtually nothing about making patterns and made it round because I couldn't think of another way to do it. I'd never do it the same way today but I may as well use it.

 

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Drilled and reamed to get clearance for a boring bar.

 

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Then I had to mark the middle because the idea was to mill away one side.

 

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It goes on the larger of the two saddles.

 

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Set up in the mill. The little piece of gasket material is there because the sides aren't perfectly parallel. I didn't think it would work but I lucked out this time.

 

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With half the piece milled away. The hole in the center and the surfaces on the ends will be done at the boring stage, after it is attached so it's mechanically straight.

 

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This is roughly what it will look like. I don't actually have a lot of things to do to the crankcase but they all demand an unusually high degree of precision - which is why I've put this off so long. I've learned a lot in the last 7 years.

 

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Wonderful job as always. Seems like you're really picking up the pace lately.

 

Do you know if the flatness of the plates matches the flatness of the jugs?  I'm not sure what the tolerance would need to be but obviously if they are significantly off that would be an issue.

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No. Neither surface is scraped, at best it was planed but I'm hesitant to change them. As to the plates, their surface is probably as flat as the jugs. I may put a gasket between the case and the blocks - probably annealed copper. There are many measurements that still need to be taken like the exact height of the pistons etc... since I never had the engine assembled or complete there has been a fair amount of guesswork combined with the provision for later adjustment. What doesn't show is that I've been thinking about how to solve the crankcase problems for years so I'm not guite diving in with my eyes closed. I think align boring these two caps and then the camshaft hole to accommodate a center cam bearing are the most challenging part of the job. I still don't know how the device that advances the boring bar works...

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2 hours ago, JV Puleo said:

 I still don't know how the device that advances the boring bar works...

 

I would think it would advance carefully... ;)

 

I guess if you set the jugs down on the plates and they don't rock around it is probably good enough.  If the jugs were planed then maybe you could run the plates on a planar/surface grinder.  I can't remember if you have either of those (I know I don't).  Probably even just an end mill would be sufficient.   How well do the jugs fit to the casting?  I'm not 100% sure I even know what I'm talking about here but it did jump into my head whilst reading your post. 

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I have both although I still have to put the motor on the planer. I did think of surface grinding the plates but I'm not convinced it will make a difference. I was thinking of scraping the crankcase just before attaching the blocks but I've never scraped before so I'd have to practice on something else first. I do have a surface plate that is probably large enough to use as the flat surface and I have a long straight edge but I suspect its too narrow (It was made for doing lathe ways.) I have milled the top of a crankcase with a wide facing mill but in that case I had to remove .035 to eliminate some welds. This case is probably as flat as it was when it was new but, as you know, I'm not overly impressed with the engine work the Mitchell-Lewis company did. I have to plan the next steps carefully because I'll be drilling the crankcase and putting in some brass inserts for attaching bolts. I want to have everything in hand first so each insert can be put in without disturbing the setup.

 

I will also have to make a boring bar and tooling to center it as well as figure out how to attach the boring bar advance mechanism to the bar I'll be making. The boring bar I have is 1.25 in diameter, too big for boring the saddles, so there will be a certain amount of experimentation going on. It was partly because I knew this was going to be challenging that I put it off until I had a lot more experience.

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I milled the sides of the water pump clamp down using the base as the register point. In as much as I can measure, the sides are now perpendicular to the base.

 

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It is just about the right size...of course given Mitchell precision, the saddle is wider on one side than the other but not by much.

The engine stand was given to me by a friend who was the auto shop teacher at a local High School. When they closed down the department (because, of course, no one needs to know that stuff any more) they threw it in the dumpster. My 3-jaw chuck, small 4-jaw and 3/4 Jacobs chuck came from the same dumpster.

 

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Most of the day was spent thinking about how to go about the next steps and looking to see if I already had what I'll need. Not to surprisingly, I had more than I'd thought and didn't have what I thought I did have. I'll have to order some materials but not too much. I also put this "dummy" cam shaft in. It is 1" bar with a long keyway. This will be part of the setup to line bore the saddles. In the middle you can see what's left of the cheesy Mitchell center cam bearing. Rather than make a real bearing they used a spring loaded piece to press down on the cam against Babbitt "half bearing." Making something to replace this will be a real challenge... even if I wanted to keep it, it would be a major problem because pouring Babbitt into an oil soaked aluminum case is not a good idea and it would still have to be bored. I have an idea but I am certain it will change before I make anything. When all the machine work is done I plan to have the case vapor degreased.

 

 

I also plan to bore out the old main bearings and make bronze shells that can be Babbitted.

 

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Ah, now were getting to the heart of the engine! I've been looking forward to this part of the build. That's an odd looking camshaft set-up. It looks as though they were relying to some degree on valve spring pressure to keep the shaft located in it's centre bearing. Are there any machined faces under there that would accept a bearing cap? 

 

Hopefully you have access to a proper line boring machine. Or perhaps you have previous experience in this field. I attempted my first home-made boring bar job recently, and it was a little tricky to get it right. I certainly cannot offer guidance, as I am a complete novice in this field. 

 

But if I may mention two unexpected pitfalls which I did not anticipate when thinking it through. One was the shape of the single HSS cutting tool. Too much rake in the grind, and the cutter will dig into the alloy bearing surface. The small amount of flex in the 36 mm bar, combined with the necessary clearance in the home made bushings supporting it, allowed the cutter to dig in if you went too hard or attempted more than .003"-.005' each cut. Just barely enough back-rake to give clearance seemed to work best. The other problem was that I needed more clearance for the scurf to flow out of the bearing. And more scurf clearance on the boring bar increases the possibility of flex. So it was a slow job.  I tapped a stud into the end of the bar in order to drive it with a cordless drill, and then controlled the feed with my other hand against the other end of the bar. I final-finished with a brake cylinder hone on an extension bar.  Primitive and agricultural, no doubt, but the camshaft now has a nice feel, with close to my target clearance of .003" in each of the four bearings. Hopefully it will hold up OK.

 

Good luck with yours, JV. It seems to have a lot of camshaft spanning between bearings. Is the shaft only one inch, or is that just the size of the test set-up?

 

Edited by Bush Mechanic
clarification (see edit history)
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The shaft is 1" in diameter, the same size as the bar with a keyway that is in there. The original center bearing support was a spring loaded plunger of sorts... I'll photograph it when I get to the shop. It's too odd to describe without a picture.

 

I do have an AAMCO line boring rig for the mains and will try to adapt it doing the cam and the magneto/water pump shafts but as yet I don't know how.

Edited by JV Puleo (see edit history)
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For the torsion plates I made a paper template and glued it to the the steel.

 

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Then drilled the two center oles and put pins in them. This keeps both plates aligned with each other. After that it was just a matter of drilling the remaining six holes. The center holes give me an easy way to bolt the crankcase to the mill table or to the boring fixture I made a long time ago out of a scrap lathe bed.

 

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Then I chased out the threads in the crankcase. There were studs here and the Mitchell method of securing them was to cut a slot on the end and spread them with a chisel...rather than use a lock nut. This made taking them out a real chore and it didn't do the threads any good. I probably should put threaded inserts in the holes but I'll wait on that...

 

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I torqued them up to 25 lbs, not being entirely comfortable with the threads in the low grade aluminum that was used then. I don't think that actual torque spec is too important as long as they are tight and the pressure is uniform.

 

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These should stay in place until all the crankcase machine work is done.

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Joe, it looks like you are getting right down to the "guts" of your engine project.  Redoubtably, your Mitchell will be very much "improved" by your touch yet still being improved with keeping the vintage design in the forefront of your process.  Keep the rally going!

Al

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I want to put brass inserts in as many of the threaded holes in the aluminum as I can. This is the proper way to do it although Mitchell just threaded the aluminum. I have at least 3 places where the steel screw has broken off because it's effectively welded itself in place. But, the brass rod I need won't be in until Friday so I'm working on a device I designed to set the cutter on the boring bar. I have one for my big boring bar but the one time I used it I wasn't completely satisfied with it's precision (though I assume some of that has to do with it being the first time I'd ever used it). In any case, it won't work for the 3/4" diameter bar I need to use to bore the magneto/water pump shaft. I started making it out of steel and decided it was too much work...for something I'll probably use twice, I can make it out of aluminum. The first step was to center a piece of 2" x 2" square stock in the lathe. I do this by putting something round that is 2" in diameter in the chuck and indicating it.

 

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Then loosen the #1 and #2 jaws and replacing it with the 2" square stock.

 

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If the dimensions are close this works pretty well. If I needed extreme precision I'd use a torque wrench to tighten the chuck but this seemed to work just fine for this purpose.

Then it was faced off, drilled & reamed to 3/8".

 

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I faced both ends then set it up in the drill press to drill 1/4" holes in the corners. It's set so that the near side is flush with the side of the vise. That way, I can rotate it 90-degrees and have the next hole in exactly the same spot.

 

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Having finished that, I cut 3/4" off one end.

 

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And faced the sawn side. I wasn't all that happy with the facing on the short piece so I surface ground it. It wasn't out much but it's better now.

 

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The corner holes on the short piece now get drilled and reamed to 7/16 for press-in threaded inserts - again using the setup on the drill press which I hadn't disturbed.

 

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So far, the pieces look good. The threaded inserts came in at the end of the day so Ill be able to continue with this tomorrow.

 

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Edited by JV Puleo (see edit history)
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17 hours ago, JV Puleo said:

I want to put brass inserts in as many of the threaded holes in the aluminum as I can. This is the proper way to do it although Mitchell just threaded the aluminum.

 

I am looking forward to seeing how you do this. I had already been thinking of bushing the existing holes through the Humberette crankcase with brass to help stop the steel corroding. Especially as I had considered using stainless for the nuts and bolts. Although more expensive to make they will not need nickel plating.

Edited by Mike Macartney
a couple of words left out (see edit history)
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I think it will be pretty straightforward. The only fly in the ointment is that the inserts I'd like to use aren't made so I'll have to make them myself. But, you are as well set up as I am for that so if it works it is well worth doing. The critical aspect is that there has to be enough room around the hole for the insert. I can't do it with the bolts that hold the sump on because the little flanges some screw into aren't large enough. I may do it where it's possible. Luckily, none of those bolts are broken off in the holes.

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I made quite a lot of progress today on the device for adjusting the boring bar. The threaded inserts came in...

 

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So I pressed them in with my shop made hydraulic press.

 

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For some reason they didn't seat quite flush.

 

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So I surface ground them. This is not the right wheel for grinding aluminum so the finish isn't perfect but that's a small matter. It is flat.

 

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Then I set the piece up in the mill to make the hole for the boring bar.

 

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My 47/64 drill is too long to use in the mill so I drilled and reamed the hole on the drill press.

 

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To get this...

 

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I then milled a slot in the larger piece for the micrometer spindle.

 

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This will give you an idea of how it works. The micrometer head will be adjusted so it's on zero when touching the boring bar. I'll add .375 (half the diameter of the bar) to the measurement so a micrometer setting of .125 should make a 1" hole.

 

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I also drilled two holes so I can reach the set screws that will hold the boring bit and started milling flutes in the sides. It will be a lot easier to adjust if I can see the pieces. I suspect this will be a bit clumsy to use but if it gives me the precision I'm looking for it will be worth the effort.

 

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This morning I came up with a way to hold the boring bar tool so I could turn the end where the micrometer head goes.

 

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I had planned to go further but got worried that I was coming too close to the slot... if I make another one for the big boring bar I'll change the design a little.

 

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This is as far as I can go until one of the two micrometer head's I've ordered comes in. I decided not to use this one because it will measure 10th of a thousandth and I'd rather save it for the tool I'll probably make for the big boring bar.

 

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Then, because the brass rod came in, I started on the threaded inserts.

I'm threading the outside with this lathe threading tool - it's from India. The workmanship is quite good but I've decided its really best for fairly small, fine threads.

 

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All threaded...

 

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Then I drilled with a #7 drill - the size of 1/4-20 threads.

 

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And cut it off at 1/2"

 

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I also checked the thread with this nut from my lifters since it was threaded with the same tap I'll be using here.

 

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I made 4 of them. I'm not thrilled with the first two so tomorrow I'll probably make a couple more. It takes a few to get a system going.

 

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I finished the threaded inserts... trimming them to size...

 

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Then tapping the center.

 

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I ended up making 7 of them (I need 4) and now I can't tell which ones I wasn't happy with so I guess they are all good.

 

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I also made the larger ones but forgot to take a picture. Once I had a system this went quite fast.

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Questions Joe,

 

When making or putting in the inserts, do you:-

  1. Drill out the original thread in the aluminium casting and tap a new thread for the brass insert at a larger size?
  2. Do you not drill all the way through the aluminium so that the threaded bush does not unscrew through the other side while you tighten the bolt?
  3. Do you lock the brass threaded insert in place with thread lock, or something else?

With the boring bar tool you are making:-

Apart from 'blowing me away' with the design and build.

  • Is it for adjusting the amount of cut of the boring bar while the boring bar is still mounted in the part that you are line boring?  If so, designing that must have taken a lot of thought.

 

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With the inserts, I will drill through the appropriate piece of aluminum, thread and screw in the brass insert with a little Locktite on the threads. I have a trick for that too to make the insert bottom exactly flush with the top of the case. I may get to this today but before I do it I want to get a new 7/16-20 tap as the old one I have has a long taper and I'm not certain I have enough room to use it.

 

As to the boring bar tool, yes, it is intended to make it possible to adjust the diameter of the bore on the bar while it is mounted on the part. Once set up, you do not want to disturb it.

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3 minutes ago, JV Puleo said:

As to the boring bar tool, yes, it is intended to make it possible to adjust the diameter of the bore on the bar while it is mounted on the part. Once set up, you do not want to disturb it.

 

So am I correct in assuming that with this sort of boring bar you only take one cut? Or, am I missing something from my understanding of this process?

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No... the tool should allow me to adjust the cutting tool so I'd take a cut, put the tool back on and readjust, take it off and make the cut. The idea is to be able to make really fine adjustments. It will be tedious to use but if it works accurately it will be worth the effort. I have run into a snag though. There is no way the crankcase will fit on the mill table so that I can get the holes that have to be drilled under the spindle. The arms that stick out to mount it make it impossible to move it in far enough. I've thought of a possible solution but, of course, it will require making more fixtures. I want to put the holes in with an end mill because the original holes look as if they were drilled freehand through the crankcase and the top of the clamp. Since I'm making the top half of the clamps I have to get the two holes perfectly centered and I have to be able to clamp the top half to the crankcase to do that. This is an occasion where a Bridgeport mill would be really useful since the head is mounted on an arm that can be pulled out but I don't have one and I'm not about to buy a different milling machine for one job.

 

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I think I'll make some arms that extend out from the table to the front and mount the crankcase so it faces in perpendicular to the table rather than parallel. I had anticipated that this might be a problem so it isn't a complete surprise but the problem is more difficult than I'd thought. Fortunately, the holes don't have to be super precise as long as the cap screws that hold the two pieces together line up.

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So, while I scrounge for material to use setting up the crankcase I started on the boring bar guides. This is two pieces of 1" x 2" aluminum. I put them on the surface plate and clamped them together.

 

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Then drilled a #7 hole for a 1/4-20 screw and set a stop on the drill press so I could drill the upped piece out to 1/4".

 

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Then tapped the lower piece with this long pulley tap.

 

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The two pieces screwed together. The idea is to machine them as one piece so that the guides for the boring bar will be is perfect alignment with each other.

 

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Oh... and about 4 or 5 years ago I visited Dunster Castle with a friend of mine. When I made these doors for the shop he insisted I was overly influenced by the castle's enormous oak doors.

 

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Edited by JV Puleo (see edit history)
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I continued with the boring bar guides today. First putting two center holes in exactly 5-11/16 apart - that is the center to center measurement for the gears.

 

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Then drilled and reamed both holes to 1".

 

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As near as I can measure they appear to be right on but they are probably a few thousandths out. I don't think that is critical as helical gears are a little forgiving.

 

Then I sawed about 1" off one end and milled the ends square.

 

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And broached a 1/4" keyway in the short end. This end will attach to the keyed shaft in the camshaft bearings.

 

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The two pieces should be mechanically identical as long as I keep them in the same alignment.

 

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I also drilled and tapped the keyway end, opposite the keyway, for 3/6 set screws.

 

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And was able to take them apart. I still have to deburr the threaded hole and press in a couple of bushings but these pieces are nearly done.

 

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One aspect of this that I was worried about was keeping the boring bar rigid. That is essential for boring a smooth hole and last night a way of tightening the guides on the keys shaft occurred to me. I drilled and threaded the ends for a cap screw. I put fender washers under the screws and was able to tighten the guides up against the crankcase.

 

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This is what I'm striving for. It will need a center support which will be made from a flanged pillow block but the really critical issue, did the two ends line up and leave the bar movable seems to have worked out.

 

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In order to position the bar perfectly the center of the bar must be 45mm above the magneto bracket. This is because virtually all mags have an armature center line of 45mm. It made them interchangeable between cars. There are a few that are 50mm but they were rarely used in automotive work. In order to do this, I ground this piece to 1.397" - 45mm less .375, half the diameter of the bar.

 

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Here it is. So far, it's gone well. The bar moves easily. The bushings in the guides were lapped to  a sliding fit in he bar so I was quite relieved when I was able to put it together and it moves freely. Also (although you can't see it here) it looks as if it aligns perfectly with the saddles. Tomorrow I'll make the center mount. Then I have to figure out how the device that advances the bar while turning actually works. I've had it for years but so far I've yet to understand it.

 

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The bar is turned with an electric drill. I'm going to use the feed mechanism from my AMMCO boring bar. I've had it for about 5 years but until today I didn't know how it worked. Necessity being the mother of invention, I finally figured it out. It's pretty hammered from the original owner so I'll have to fix a few things first but I think the additional pieces I will need to use it with this 3/4" bar are going to be fairly simple and won't effect the original tool. I'm relieved to have figured it out. It's one of those little things that's been nagging at the back of my mind for a long time.

 

More photos tonight...

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