CBoz

Manufacture part from CAD file?

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Hello Folks -

 

I have already had a CAD file created for a rumble seat step plate I need to have reproduced. I'm looking for a shop that can take the file (STP format, pretty generic) and make the part out of aluminum.  Any leads?

 

 

Untitled.thumb.jpg.65237785d6de0fc0f4b3f6cc12da8b3f.jpg

Edited by CBoz (see edit history)

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How many parts do you want?  One solution is to print out via 3D printing a slightly oversize model in something like Shapeways "strong and flexible" plastic at about $0.28 per cubic cm, plus set-up charges, etc.  A foundry can then take that and cast aluminum copies.  While they can also print directly in aluminum, the cost is $7.00 per cubic cm plus set-up.  Better to have a plastic master as a pattern.  

 

Find a foundry first, see what they want for draft on the pattern and their normal shrinkage allowance (~2-4% for aluminum).  Adjust your CAD model and have the plastic master printed out.

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I agree with Gary on querying the foundry first. Cattail is one that has done small quantities for the car hobby. Print out the file as a plastic part and use as a pattern. One detail I notice is your spacing between the squares on the step. You may have to widen the spaces between them to account for detail that gets lost during sand casting. There are some companies printing in metal directly from a file, however, I'm doubtful that the detail is there. Print a pattern and cast as usual.

Curious, what program did you use to create the file?

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1 hour ago, Friartuck said:

I agree with Gary on querying the foundry first. Cattail is one that has done small quantities for the car hobby. Print out the file as a plastic part and use as a pattern. One detail I notice is your spacing between the squares on the step. You may have to widen the spaces between them to account for detail that gets lost during sand casting. There are some companies printing in metal directly from a file, however, I'm doubtful that the detail is there. Print a pattern and cast as usual.

Curious, what program did you use to create the file?

Thanks for the info, Gary and Friartruck.

 

The step plate was at the other end of the country, so I had someone else create the file (I couldn't really ask the owner to risk mailing it to me) so I could decide later how to make it. It's off of a '38 Lincoln K roadster, so there really isn't any additional demand for it. The picture above was from a stp file reader I downloaded. I was thinking that rather than 3D printing it, it could be machined from a block of aluminium? At least I have the specs captured for now!

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Perhaps search under the terms CNC Machining and Hog Out. There seems to be a bunch of them, specializing in low quantity like 1-2 pieces. This actually might be the better way versus sand casting.

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Having spent considerable time working with 3D printing, CAD & CNC I too suggest 3d printing a pattern and having a foundry cast it. As other have said you will need to scale it up slightly to take into account shrinkage rate for aluminum (approx. 1/8"+/- per foot) As for machining it out of solid. It is doable but your looking at a lot of machine time. Looking at the tread pattern (square corners) EDM might be the way to go for the tread pattern.

 

Foundry work seems to get short shift lost among the high tech of 3D printing and CNC but in many applications it truly is the most cost effective and efficient way to go.

 

Here is  a 3D printed pattern and core box I made awhile back for a bronze housing for an oil pump drive. I had a friend who does backyard metal casting work his black art and

I soon had a finished casting in hand.

IMG_4133.thumb.JPG.24e22cb7ed8a8174ffc489a8f288e8a8.JPG

 

We usually think of CNC for milling components from solid. In this case since the time and wasted material from CNC were prohibitive we used the technology  to mill patterns and core boxes.

These are for the valve shrouds for a Wisconsin T-head engine as used by Stutz and a variety of other automobile and truck manufacturers.

IMG_0982.thumb.jpg.7be22f5d5b9ac8e599d329a78e338c9d.jpg

 

 

 

 

 

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Thanks all for the really good information and education! I'll be looking into it and let you know where I end up. BTW, here's the car it will be going on when done:

IMG_2223.JPG.1f5699350c33309060e5664ab64560cc.JPG

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Very nice!

 

On your 3D printed pattern - don't forget draft (slope to the vertical sides perpendicular to the direction of pull) this allows the pattern to be pulled easily from the sand. The typical angle is from 2-1/2 - 3 degrees from vertical. Also you will need to add allowance for machining. For example if you have a surface that needs to be milled or faced flat we would add 1/16" or more to the thickness to allow enough material to be removed that will allow removal of all imperfections without having the finished part end-up undersize after machining.

 

A foundry that comes highly recommended is Cattail Foundry run by the King family in Pennsylvania. They are also very good at using original parts as the pattern.

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If you only want one... I would call a local machine shop and have it CNC cut.  In todays world I would guess it would be under $300.  Not a hard part to make.  You will have to email them the file.  They will know what to do with it, and give you a quote before they start.  I would think about a free machining stainless steel like 304, tell them the application and they will help you.  It would be nice to know the original material Lincoln used?

 

Good luck, it should be easy

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W.r.t. 3D printing, I am working on reproducing some snouted grommets used in the Dodge 8. I sent my stl files out for printing and the parts came back, but something was wrong and they are not round and not straight - they snouts have a lean! I complained and over the next two or more months he was trying to sort out the problem with the printer and scaffolding. It didn't work out so he refunded my money. These were prototyping prints so at least I have something to look at and decide if it is about right (no good originals have come to light, yet).

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The other thread by CBoz on this interesting topic:- http://forums.aaca.org/topic/307438-any-good-leads-on-someone-who-can-reproduce-parts-using-cad-files/

 

3D printing is getting better, but someone needs to get CAD file drawn.

And programmable CNC machines are getting more affordable.

Edited by 1939_Buick (see edit history)

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I recently used Emachineshop .com and was pleased with the results.  It was a simple 2D shape made from  1/4" steel  (I supplied a .dwg file) but they quoted quickly and I had my part in a week.

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Here's a screen shot of the AutoCad drawing.  It's going to be used to mount wind wings on the Dodge.  I had been looking for some time for some wind wing mount brackets and the choices were pretty much limited to either clamp-on style (on the windshield stanchions) or brackets designed to thread into a tapped hole (or bolted through) the stanchion.  I wasn't too keen on either method and did not want to drill holes in the stanchions.  A fellow Dodge brother posted a photo of how someone mounted them to his car (2nd pic), which to me seemed much more elegant than clamp-on brackets.  The flat bar bolts on in place of the windshield pivot washers, giving a place to mount the wind wing brackets.  I simply refined the idea to make them look more integrated.  If anyone wants a copy of the AutoCad file, I'll be glad to send a copy.  I'm using Ford Model A-style brackets.  Cost was $104 for 2 of them, including the steel and shipping.

Wind Wing Bracket.jpg

Wind wing -1.jpg

Wind Wings-2.jpg

Wind Wings-3.jpg

Wing bracket.jpg

Edited by MikeC5 (see edit history)
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On 4/5/2018 at 8:18 PM, MikeC5 said:

I recently used Emachineshop .com and was pleased with the results.  It was a simple 2D shape made from  1/4" steel  (I supplied a .dwg file) but they quoted quickly and I had my part in a week.

Sent my stp file into them; will let you know what I hear back.

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