Delrin Revisited!
Delrin Revisited!
Bet you guys thought this subject had gone away for a while?
Well, I've run into a new problem I haven't seen discussed here. I've been using delrin tenons for a while and was completely happy with it. UNTIL, I ran out of the rod I was cutting tenons out of and started using another. After running into problems with loose fit on my last 3 pipes, I did some checking. I thought I might be getting sloppy with my drilling procedure. So today after making my 4th loose mortise/tenon in a row I dug out my digital caliper. Drill bit and drilling procedure is fine, still drilling a mortise at .310 to .311 in diameter. The problem is, my 5/16" delrin rod is also .311! The rods I've measured before usually were around .313 to .315 and I got nice tight fits. But this rod is too small for the mortise I'm drilling.
Anybody else had this problem? Is it a normal occurrance? Or did I get the only delrin rod in existence thats under nominal diameter? (.3125)
Thanks
David
Confused by Delrin again!
Well, I've run into a new problem I haven't seen discussed here. I've been using delrin tenons for a while and was completely happy with it. UNTIL, I ran out of the rod I was cutting tenons out of and started using another. After running into problems with loose fit on my last 3 pipes, I did some checking. I thought I might be getting sloppy with my drilling procedure. So today after making my 4th loose mortise/tenon in a row I dug out my digital caliper. Drill bit and drilling procedure is fine, still drilling a mortise at .310 to .311 in diameter. The problem is, my 5/16" delrin rod is also .311! The rods I've measured before usually were around .313 to .315 and I got nice tight fits. But this rod is too small for the mortise I'm drilling.
Anybody else had this problem? Is it a normal occurrance? Or did I get the only delrin rod in existence thats under nominal diameter? (.3125)
Thanks
David
Confused by Delrin again!
Re: Delrin Revisited!
This wouldn't suprise me very much unless you told me that this is all the same batch of delrin from the same company. Then I'd be worried... :think:bvartist wrote:Bet you guys thought this subject had gone away for a while?
Well, I've run into a new problem I haven't seen discussed here. I've been using delrin tenons for a while and was completely happy with it. UNTIL, I ran out of the rod I was cutting tenons out of and started using another. After running into problems with loose fit on my last 3 pipes, I did some checking. I thought I might be getting sloppy with my drilling procedure. So today after making my 4th loose mortise/tenon in a row I dug out my digital caliper. Drill bit and drilling procedure is fine, still drilling a mortise at .310 to .311 in diameter. The problem is, my 5/16" delrin rod is also .311! The rods I've measured before usually were around .313 to .315 and I got nice tight fits. But this rod is too small for the mortise I'm drilling.
Anybody else had this problem? Is it a normal occurrance? Or did I get the only delrin rod in existence thats under nominal diameter? (.3125)
Thanks
David
Confused by Delrin again!
Re: Delrin Revisited!
Same batch, same company, same order. I don't know if it was all cut from the same stock. But it was all ordered at the same time!bscofield wrote:
This wouldn't suprise me very much unless you told me that this is all the same batch of delrin from the same company. Then I'd be worried... :think:
Thats where I got this stuff! I'm hoping it isn't a normal thing, just ordered 12 ft more from them before I discovered the problem.hazmat wrote:I had to order delrin from a couple of different places before I found a place that fits my needs. I ended up getting it from online metals, and it's perfect every time.
Re: Delrin Revisited!
OK, now I'm worried,bvartist wrote:Same batch, same company, same order. I don't know if it was all cut from the same stock. But it was all ordered at the same time!bscofield wrote:
This wouldn't suprise me very much unless you told me that this is all the same batch of delrin from the same company. Then I'd be worried... :think:
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Re: Delrin Revisited!
That's the first time I've ever heard of that. I'd send them an email and ask WTF, and a refund/exchange.bvartist wrote:Anybody else had this problem? Is it a normal occurrance? Or did I get the only delrin rod in existence thats under nominal diameter? (.3125)
Dan, Doesn't that require a metal lathe? I don't think my turning skills are good enough to accomplish that on a wood lathe. But it would simplify things!bluesmk wrote:I haven't. Although I use 1/2''. I cut my tenon's for each stem.
That was my first thought, but I measured the diameter of the mortises and they were fine. Usually as a bit dulls, it will tend to "wander" a little and drill a hole thats slightly larger. My problem is definitely the delrin.hazmat wrote:Is there any chance at all that the bit you're drilling your mortise with got jimmied up at all?
The only bit I know of that won't leave the little ridge is an end mill. Unless you want to use a standard point bit and chamfer the end of the tenon to match.And while we're talking about bits.. is there such a thing as a brad-point bit that doesn't leave a lil ridge in the bottom of my mortise around the draft hole???
Jump in anytime! I hope to have a metal lathe, and a place to use it someday, so little tidbits of wisdom are always welcome!bluesmk wrote:I'm sorry, I just jumped right in, didn't realize you were working without one.
Some good news! My new order of delrin came today. This time I checked all the lengths I bought and they are all .313 diameter! I think I just happened to get a piece that was missed by QC in the manufacturing process. Good thing it was only a 1 foot piece!!!! I should be set now!(until I run out again!)
David
Not sure what grade Delrin you are using, but it's probably extruded stock. The tolerance on extruded stock is something like +/- 2% of the stated diameter. It can vary that much from one end to the other. I machine a lot of different plastics at work and have learned not to trust stock to clean up at nominal size. Not the answer you were looking I know, but I believe you're best off to measure each piece and adjust your drill size until you can get a lathe. Just my $.02
Joel
8O 8O 8O 8OJBW wrote: Not the answer you were looking I know, but I believe you're best off to measure each piece and adjust your drill size until you can get a lathe. Just my $.02
Just some rough calculations, for my delrin thats .311 in diameter, I'd need a 159/512 drill bit. Do they make such a thing????
I'm with you JBW. I was supervisor for many years as a tool grinder for plastic mold injection and one thing I can say for sure is nothing is as it seems. On any given job on a mold each and every part of it must be checked even if we did receive stock parts that should theoretically just be inserted and work correctly. I have zero faith in manufacturing. It'll bite you in the ass every time.JBW wrote:Not the answer you were looking I know, but I believe you're best off to measure each piece and adjust your drill size
I dont think I ever turn off my digital veneer. It's my most used tool.