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Noob machining Delrin - Seeking advice

Analog

Plastic
Joined
Apr 10, 2021
Hello everyone, I am attempting to machine thin delrin shims using a "2 stage" hole saw and drill press.

I have tried different methods and drilling speeds but I'm encountering an issue where the outer hole saw leaves rough finish. The inner hole saw cuts fairly cleanly every time. Both hole saws are Dewalt brand with fine teeth. I've tried using drilling oils and compressed air to clear the drilling chips which has helped, but I still have rough outer edges which takes further trimming and just doesn't look very good.

I am looking for consistent cuts as I have a lot of these shims to make!

Any advice on other methods or tips to improve my process would be greatly appreciated. I have attached a few images to show what I am working with and the results I am trying to improve.

Thanks!

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Get a hole saw with more teeth, like one for cutting metal, and feed slower.
 
+1 on Dualkit's response. Also, use a fresh piece of firmer backup material for each cut. Put a sheet of Delrin on top of the wood, and find a fresh location for every cut.
 
You are driving the smaller hole saw THRU, and cleaning up the crap on the ID.

When the larger hole saw is close to breaking through, the ring
breaks free, BECAUSE THERE IS NOTHING HOLDING IT. However the sheet
is being held, and that looks pretty good.
 
The idea of using a metal-cutting saw is a good one.

Another idea is to make a single edge tubular cutter. To do this, get a steel/brass/whatever pipe or tube of the required diameter, then sharpen one end of it with a high rake angle. So, basically you sharpen the inside edge of the tube. Then mount the tube in the drill press the same way as a hole saw. It should make a very clean cut if done correctly.
 
Hello everyone, I am attempting to machine thin delrin shims using a "2 stage" hole saw and drill press.

I have tried different methods and drilling speeds but I'm encountering an issue where the outer hole saw leaves rough finish. The inner hole saw cuts fairly cleanly every time. Both hole saws are Dewalt brand with fine teeth. I've tried using drilling oils and compressed air to clear the drilling chips which has helped, but I still have rough outer edges which takes further trimming and just doesn't look very good.

I am looking for consistent cuts as I have a lot of these shims to make!

Any advice on other methods or tips to improve my process would be greatly appreciated. I have attached a few images to show what I am working with and the results I am trying to improve.

Thanks!

View attachment 318640

View attachment 318641

View attachment 318642

View attachment 318643

How many are you making? Drilling plastic with a hole saw is a pain in the neck.
My experience with similar part, HDPE 3.94" OD
Cut strips of material on table saw.
Cut to squares on power miter.
Fixture and drill the center hole with step drill.
Stack 60 on a mandrel, turn OD on lathe
Results are beautiful.

CarlBoyd
 
Stack the suckers up in some sort of clamp stack. Simple enough to make but I will design one for only $300.00. Drill inner hole through all. You get a clean inner hole. Drop a clamp into inner hole and drill outer hole. $50.00 to tell you how to do that.
BOBW is telling you what is happening. Doing it for free too. Nice guy. But not telling all.
Mastercard, Visa, Amex accepted.
You have a "lot" to do. That is not a number. 6 is a lot more than 2. Exactly how much is in a Shitload ? MIT cannot figure that one out.
 
+1 on Dualkit's response. Also, use a fresh piece of firmer backup material for each cut. Put a sheet of Delrin on top of the wood, and find a fresh location for every cut.

And there is your answer. A fresh spot for every hole.
 
The idea of using a metal-cutting saw is a good one.

Another idea is to make a single edge tubular cutter. To do this, get a steel/brass/whatever pipe or tube of the required diameter, then sharpen one end of it with a high rake angle. So, basically you sharpen the inside edge of the tube. Then mount the tube in the drill press the same way as a hole saw. It should make a very clean cut if done correctly.

I think Delrin is going to be much too hard to allow that to work well, at what appears to be 1/8" thkns. You will likely start melting the material before achieving a complete cut. OTOH, using a tube as the basis for a trepanning tool is something that works pretty well, if you have the wherewithal to make it.
 
How many are you making? Drilling plastic with a hole saw is a pain in the neck.
My experience with similar part, HDPE 3.94" OD
Cut strips of material on table saw.
Cut to squares on power miter.
Fixture and drill the center hole with step drill.
Stack 60 on a mandrel, turn OD on lathe
Results are beautiful.

CarlBoyd

Also my preferred method for making multiple plastic disks. Stack 'em on a mandrel and let the corners fly.
 
Yep, backup but a thick one. So that the backup is left with a round stump like for a punch. And does the rpm's of the two drills match? See the outer edges of the disks.

Taking the word punch a little further. I would machine a punch/die or whatever you want to call it. Very easy to do on a lathe with a scrap piece of metal. Do this all the time and keep every punch I make for the next time.
 
I made a cutter to cut cork gaskets that may help. The cutter OD 1.500 , ID 1.437 . The depth was 1.000 and a bevel was turned on the ID. I turned a CRS 1-1/2" x 4" with a center thru hole 1/4" diameter to push gaskets thru. The shaft was turned to .620 x 2.500. I found that power wasn't needed to cut cork gaskets. Just a down stroke on the quill.
You would need perimeter slots or points like a multi-spur drill.
Might be worth a try if the bit you need is not available. I used a Forstner bit to bore the inner hole 1.250 which was bored first.
 
They're expensive, but I think a Greenlee hole punch would do a great job on these. Perhaps you can find an electrician friend that has a set that you could try.
 
Hello everyone, I am attempting to machine thin delrin shims using a "2 stage" hole saw and drill press.

I have tried different methods and drilling speeds but I'm encountering an issue where the outer hole saw leaves rough finish. The inner hole saw cuts fairly cleanly every time. Both hole saws are Dewalt brand with fine teeth. I've tried using drilling oils and compressed air to clear the drilling chips which has helped, but I still have rough outer edges which takes further trimming and just doesn't look very good.

I am looking for consistent cuts as I have a lot of these shims to make!

Any advice on other methods or tips to improve my process would be greatly appreciated. I have attached a few images to show what I am working with and the results I am trying to improve.

Thanks!

View attachment 318640

View attachment 318641

View attachment 318642

View attachment 318643

That is why they are called "Hole Saw". They are sharpened to cut a clean hole and that is exactly what you are getting.
They are sharpened on a slight angle so the outside cuts clean thru before the inside edge can finsh. Look at your material. You always have a clean hole on the outside.
 








 
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