Window Transmission Gears 3D Printing

TravL350

TravL350

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I am moving this thread out of the Classifieds section now that it has turned into more of a project than a WTB.

I got the gear out of the transmission last night and started modeling it in SolidWorks this morning.

I had though this gear was going to be stripped, but it turned out to be perfectly fine.
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That allowed me to get accurate measurements from a good part, but now I don't want to cut the plastic off of the metal core it is overmolded to. Once I get my hands on a stripped part, (Andrew W. is very kindly sending one) I can cut it apart and measure the features on the inner part. Then I'll cut the reverse of those out of my 3-D model so the two parts can be mated together.




Here's some of the process and where I stand with the 3D model:
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this is great, thanks for taking this on. How about making one gear out of brass or similar instead of the 2 part plastic/steel process? The plastic was probbaly used to keep it quieter but i don't think anyone would care now.
 
Thanks, Steve - I wish I could make a machined one, I just don't have the abilities or tools. I still intend to get in touch with Al Meekins though to see what it would cost to do a brass one. I think it would be quite expensive, but who knows?
 
Hi Traivs,

I'm not sure what your plan is for the two piece aspect. If you make it a two piece part with a seam down the middle of the gears, perhaps you can stagger the seam on each tooth. Also add alignment pins and perhaps a channel running the circumference for the glue. Looking forward to the updates!

Unrelated: If that is a titanium ring that you are wearing I would remove it if you doing any work in the garage. I'm sure you know but if you smash your finger, it's a lot harder to cut through and bend titanium compared to precious metals.
 
Markos said:
Hi Traivs,

I'm not sure what your plan is for the two piece aspect. If you make it a two piece part with a seam down the middle of the gears, perhaps you can stagger the seam on each tooth. Also add alignment pins and perhaps a channel running the circumference for the glue. Looking forward to the updates!

Unrelated: If that is a titanium ring that you are wearing I would remove it if you doing any work in the garage. I'm sure you know but if you smash your finger, it's a lot harder to cut through and bend titanium compared to precious metals.
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Not sure of the plan...that makes two of us! ;) As far as I can tell, the metal inner part has teeth on it to apply the torque to the plastic to avoid breaking loose and spinning
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I like your idea of staggering the seam along the teeth! That would allow me to still only have one 3D part which is cheaper.
I was thinking of keeping the seam away from the teeth altogether and just having a base part the metal core could press into, plus a plastic "cap" that would be glued on top. Like I said...still not sure which way to go here. Must do more thinking
 
TravL350 said:
Not sure of the plan...that makes two of us! ;) As far as I can tell, the metal inner part has teeth on it to apply the torque to the plastic to avoid breaking loose and spinning

I like your idea of staggering the seam along the teeth! That would allow me to still only have one 3D part which is cheaper.
I was thinking of keeping the seam away from the teeth altogether and just having a base part the metal core could press into, plus a plastic "cap" that would be glued on top. Like I said...still not sure which way to go here. Must do more thinking
Click to expand...

Yeah knowing that the metal has teeth changes things. I would use your pressed in approach. You can stop the recesses for the metal teeth at the halfway point so that the metal is centered properly. You can also add a small lip that the metal passes over so that it snaps into place. No glue required
 
Can't a new one be popped out on a lathe and mill? I have the tools, but haven't learned to do gears yet. It's something I'm wanting to learn...when time permits. Brass or Aluminum would be nice to work with.
 
After spending 40 years in the industrial gearing industry, I can tell you this-

You would be best served to either source a used unit to scavenge what you need, or change out the complete unit to the e24 rear drive cited by a few of the folks here who have done it.

From the pics you provided, a simple description of the gear minus excessive technical jargon, would be-

Right hand worm gear, 1.0 module, single start, 48 teeth. The material is probably delrin or some type of acetal plastic molded around an aluminum hub, machined for a press fit. Plastic material is often used for cost and weight consideration. The configuration of this gear isn't offered as a stock product by the usual players here stateside like Stock Drive Products, PIC Ddesign, and Ametric. The closest gears that these folks offer have 50 teeth and just wouldn't work because of your fixed center distance. Metric 1.0 module gearing is very close to 24 Diametral Pitch (inch) gearing, and with the worm gear made from plastic, if you could find an off the shelf 24 DP gear with 48 teeth, it would probably work. 48 teeth again, is just not available as a stock product from folks like Boston Gear, Martin, Globe etc... If you were to purchase a custom gear from someone who has the tooling, I would expect they'd charge in excess of $300 due to material and set- up. To get a part like this down in the $20 range, I'd guess you'd have to buy more than 100 units.

You may have some success with 3D printing, but IMHO it'll be a lot of work for a part that won't have 1/2 the integrity of a salvaged used gear.

If you like to tinker, it looks like a fun project.
 
Thanks, Ed! Great info. I can assure you I am merely a tinkerer. One of my goals here is to see if 3D printing is a viable option for this type of part (small, simple, plastic) on the coupe. We're only talking about $15 here, so plenty of room for experimentation. That's where rapid prototyping gets its name after all. Cheap, easy, and fast way to find a working solution. As to long term durability, we will see...

Stay tuned,

Travis
 
Markos said:
Hi Traivs,

I'm not sure what your plan is for the two piece aspect. If you make it a two piece part with a seam down the middle of the gears, perhaps you can stagger the seam on each tooth. Also add alignment pins and perhaps a channel running the circumference for the glue. Looking forward to the updates!

Unrelated: If that is a titanium ring that you are wearing I would remove it if you doing any work in the garage. I'm sure you know but if you smash your finger, it's a lot harder to cut through and bend titanium compared to precious metals.
Click to expand...

Ha, that's why my ring is Tungsten Carbide. It's sintered and super tough, but when it's hit hard enough, it breaks rather than bends. Of course I usually remove it before getting heavy into wrenching.

Ian
 
Quit wearing my wedding ring in 2006 when I was restoring our house, now it doesn't fit me anymore. I know a few people who have tattoos for wedding rings, was thinking of going that route as well.
 
adawil2002 said:
Quit wearing my wedding ring in 2006 when I was restoring our house, now it doesn't fit me anymore. I know a few people who have tattoos for wedding rings, was thinking of going that route as well.
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You can do that because your car is already restored. That is a risky move for those of us with a rusty e9 disaster in the garage. :D
 
adawil2002 said:
Quit wearing my wedding ring in 2006 when I was restoring our house, now it doesn't fit me anymore. I know a few people who have tattoos for wedding rings, was thinking of going that route as well.
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that happened to me, i just had it heated and enlarged (3/4 of a size) ... now it fits fine
 
Can't you machine a 1-piece out of delrin? I know a forum member has made a part using that material w/success.....unsure about th price or if it is correct material to make a gear from?

-Mo
 
it probably wouldn't hold up on the inner pressed/splined part would be my guess

m73 said:
Can't you machine a 1-piece out of delrin? I know a forum member has made a part using that material w/success.....unsure about th price or if it is correct material to make a gear from?

-Mo
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Stevehose said:
it probably wouldn't hold up on the inner pressed/splined part would be my guess
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Sounds right. What a incredibly complex little part! (for reproduction at least :) )

Guess why most car parts are made on a giant-scale to justify the engineering requirements.
 
Thanks to Andrew kindly (and quite speedily) sending me a stripped window gear, I was able to pull out the toothed metal core and take accurate measurements to add to my 3-D model.
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I added some features to retain the metal core once it is press fit into the plastic.

I ordered a couple parts to be printed from nylon, as well as one to be made from binder jetted stainless steel/bronze.
Though probably not the ideal alloy, this is the only metal option that is remotely affordable!
Here is what the stainless/bronze part will look like:
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The spokes cut into the center are not just to look cool, but to reduce shrinkage in cooling (hopefully). I'm not getting my hopes up too high for the metal part, because the resolution is pretty low, but we will see!

I should have the parts in about a week

Travis
 
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