Custom PEEK Washer for Impact M3

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jbravo103

jbravo103

Member
Jan 20, 2019
386
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North Dakota, United States
I’m looking for someone that can make me a custom PEEK washer for my Impact M3. This would be used help reduce or eliminate low first shot(s) caused by valve rod stiction. The washer is used in front of the E103, PUR90 oring (which also needs to be replaced with NBR90 or Viton).

This solution was developed by fellow AGN members and is documented in this thread.

Dimensions for the washer are shown below:

image001.png
 
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I could probably do another one I have to make one for M3 I have apart now that I'm working on it's got to be a pretty tight fit on the rod I got plenty of viton orings also I noticed if mine sits a month it still does it I would recommend a few drops of silicone oil in the fill port and then fill it to keep it lubed up I'm a self taught on the lathe so it may not be perfect as far as angle wise
 
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I’ll order up some PEEK and make some. I didn’t have any plastic that size on hand, so I made a test piece out of aluminum and scaled the width from the drawing posted above, I’m away for the day but I think it was 2.5mm. I used a reamer I have for the bore and it measured 2.98-2.99mm, so if that works for the bore, that will help keep the costs down if I don’t need to use a boring bar.
 
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I built 5 or so back when we all were involved in that topic. I just used a 3mm drill bit and they slid very nicely over the valve rod. The most important thing is the final fit. If you don’t get the angle exact, it changes the seating depth. It’s not the end of the world if you don’t get the angle right because during the final fitting you make sure you can’t see any part of the oring in the plenum refresh hole. I used a Viton but still used the other little black oring too. If you see oring through the hole, you have to surface the disc and make it thinner until things are right. Also during final fitting is make sure the valve rod moves freely and centered once everything is packed in there.
 
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Thanks for the additional info, getting an exact angle is time consuming, so they are usually specified as +/- 0.5 degrees. Really tight tolerances are for military and aerospace budgets :). I have my compound set to within +0.2 degrees, so hopefully that is good enough.

Drills often make slightly oversized holes, so for things with tight tolerances, I would bore it or use a reamer. I’ll have to check my drill when I get the PEEK and see how close it is to size in that material. That would be one less step if it is on size.

For a manufacturer to offer these, there would need to be a big enough market, there is not enough money in a part like this unless you are selling hundreds or thousands of them for anyone other than a small producer supplying this market. Even though it is a fairly simple part, there is some time consuming setup required that can easily exceed the time to make the parts for a small run, and plastic is expensive unless you buy a large qualtity.

I’ll report back once the plastic stock arrives and I get a sample made and see how long it takes to make them.
 
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I was just fixing to ask this question…it seems I’ve read that the issue is more about just squaring the bottom of the hole to help with the squeeze created by the drilled bottom. ?

If this is truly the case, the oring will seal to the walls and rod with the spacer, correct? As such, the surface finish is negligible since it will not be sealing there.

Fwiw, when drilling peek, I’ve found it to drill ever so slightly undersized (same as most plastics). Even reaming it’s generally a tight fit.

Dave
 
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sb327 said:
I was just fixing to ask this question…it seems I’ve read that the issue is more about just squaring the bottom of the hole to help with the squeeze created by the drilled bottom. ?

If this is truly the case, the oring will seal to the walls and rod with the spacer, correct? As such, the surface finish is negligible since it will not be sealing there.

Fwiw, when drilling peek, I’ve found it to drill ever so slightly undersized (same as most plastics). Even reaming it’s generally a tight fit.

Dave
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Oring does the sealing so yeah tolerance for the angle of .5 degree should be good
 
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