There are a many things that I learned on this forum that have greatly helped me along the path to making better pipes. Some have worked better than others and there are a few tasks that really get to me. One is when drilling acrylic the propensity for the drill channels to fill and melt against the inner wall of the airway, especially with translucent material.
The other would be removing partly cured epoxy from an airway or re-drilling it to remove the slop over.
The distaste for these two things was driven home recently boring a 6 inch acrylic stem. There is no joy in it and something occurred to me! So I have revised my procedure somewhat.
First to avoid the epoxy from entering the stem airway, don't drill it. Instead I cut my delrin and drill a 1/16 hole through it, horizontal rings on the lathe and vertical slots with the file and face it off. Next I only drill the mortise into the stem material, then epoxy galore stick in the delrin and watch the excess drip out the drain hole. Can't drip into the airway as it was not yet been drilled. For me this seems to work much better and way cleaner. YMMV
Onto my next hated task, the acrylic meltdown problem. I normally drill it with a 5/32 tapered bit, nothing special they all fill with material that when not withdrawn soon enough will heat up and melt the airway wall and in the extreme case seize and lock up. No wonder I hate it, it is a royal pain. My first attempt to solve this was to reduce the temp of the bit with a wet cloth with ice whenever withdrawn. It helped and I still do it, but it is not a complete solution. What changed is I have started to pre-bore the stem with a 3/32 which removes about 60% of the material before I drill the real airway. I now drill the delrin and stem together. This is not any less error prone than drilling with only the 5/32 but it makes drilling with the 5/32 so much easier. The 5/32 has less material to remove so the drill channels fill much slower.
While I have only used this for two recent stems that were no where close to 6 inches it really seems to be much more efficient and produce equal or better results with less aggravation. I am not claiming that I now enjoy it, just seems to be a bit more palatable. Of course, I use cutting oil.
Give it a shot, I would not mind some other opinions or some better ideas.
Fume in pace
ckr
Tasks I Hate
Tasks I Hate
Last edited by ckr on Fri Jun 01, 2007 4:28 pm, edited 2 times in total.
I haven't used acrylic in a while and when I did it was a short-lived experiment because I didn't have a decent lathe. I really can't answer that question, but somewhere in this stem work forum there's a thread wherein Marks gives me about 3 paragraphs of solid acrylic information and I believe he gives a brand name in there.
Here's the thread: viewtopic.php?t=1692&highlight=
Here's the thread: viewtopic.php?t=1692&highlight=
Hi,
Interesting ideas.
On the epoxy-the-tenon-first, drill-the-air-way-second, I had thought of that, but since the bit and material get so hot I always thought that the heat would cause the epoxy to fail and then bring you back to square one. Is this not the case? Maybe the double-drilling keeps it cooler and makes the difference. I'll try to incorporate this idea on the next few and see what happens.
On the pre-bore/double drilling with a smaller drill first, I do this also, but not for the same reasons. I started doing that for various tasks as a way of damage control/keeping my options open. If the hole is not correct, I still have some room to make an adjustment if possible. If the hole needs clearing out (like a draft hole/epoxied tenon situation) by drilling first with a smaller drill then epoxy, assemble, etc. and finishing with the larger correct sized bit I figured the hole would be cleaner and more accurate if I drill that size once, rather than running a same sized bit through which will bounce up against the sides cutting where I don't want it to cut as it clears any obstructions.
Regarding your melting acrylic problem, the first thing to do is to buy the more expensive cast acrylic rather than extruded. For me the difference was like night and day. Rather than coming out in long molten strings, the waste comes out as curly shavings. I also wet the bit down in drilling and don't drill the whole bit in one push. I do it in a few steps, removing it to wet it down and clear the channels. One reason the plastic can over-heat is that there is no where for the heat to go, down in that little tunnel, as the bit rotates at over 1200-something or more a minute. Especially when the bits flutes are clogged with molten plastic.
Interesting ideas.
On the epoxy-the-tenon-first, drill-the-air-way-second, I had thought of that, but since the bit and material get so hot I always thought that the heat would cause the epoxy to fail and then bring you back to square one. Is this not the case? Maybe the double-drilling keeps it cooler and makes the difference. I'll try to incorporate this idea on the next few and see what happens.
On the pre-bore/double drilling with a smaller drill first, I do this also, but not for the same reasons. I started doing that for various tasks as a way of damage control/keeping my options open. If the hole is not correct, I still have some room to make an adjustment if possible. If the hole needs clearing out (like a draft hole/epoxied tenon situation) by drilling first with a smaller drill then epoxy, assemble, etc. and finishing with the larger correct sized bit I figured the hole would be cleaner and more accurate if I drill that size once, rather than running a same sized bit through which will bounce up against the sides cutting where I don't want it to cut as it clears any obstructions.
Regarding your melting acrylic problem, the first thing to do is to buy the more expensive cast acrylic rather than extruded. For me the difference was like night and day. Rather than coming out in long molten strings, the waste comes out as curly shavings. I also wet the bit down in drilling and don't drill the whole bit in one push. I do it in a few steps, removing it to wet it down and clear the channels. One reason the plastic can over-heat is that there is no where for the heat to go, down in that little tunnel, as the bit rotates at over 1200-something or more a minute. Especially when the bits flutes are clogged with molten plastic.
www.TotemStar.com - Some of my pipe related art
Hi Gunnar,
I use usually use delrin for my tenons, cuts like butter, no heat there at all. I do not think there would be much even if I did not double drill. I don’t think the drill heats up until the channels fill with material and the material rubs against the airway walls. Anyway, this is what appears to happen when drilling translucent acrylic. Even if it is five minute epoxy I do not usually drill to the next day. Most of my mistakes are from being in a hurry, so I make it a point not to be in a hurry.
On double drilling I think we are both experiencing the same benefits. One, being the only exposed epoxy is the seam where tenon meets the stem mortise. Two, cleaner cuts on the inside wall – although I can’t prove it with doing it on clear acrylic.
And hey, I am using cast!! I get a small flake type of shaving and they all bunch up eventually and jam up, then they get tighter and tighter until the start to rub the wall, heat and will stick. Maybe because I am using a tapered bits but I do not get those nice little curly spiral DNA shapes like when I am drilling delrin. I think I am drilling at about 800 (Taig’s Slowest). The best defense is to use the rhythm method and pull it out, which I do frequently and the double drilling seems to extend the time the drill can CUT without getting too hot.
I use usually use delrin for my tenons, cuts like butter, no heat there at all. I do not think there would be much even if I did not double drill. I don’t think the drill heats up until the channels fill with material and the material rubs against the airway walls. Anyway, this is what appears to happen when drilling translucent acrylic. Even if it is five minute epoxy I do not usually drill to the next day. Most of my mistakes are from being in a hurry, so I make it a point not to be in a hurry.
On double drilling I think we are both experiencing the same benefits. One, being the only exposed epoxy is the seam where tenon meets the stem mortise. Two, cleaner cuts on the inside wall – although I can’t prove it with doing it on clear acrylic.
And hey, I am using cast!! I get a small flake type of shaving and they all bunch up eventually and jam up, then they get tighter and tighter until the start to rub the wall, heat and will stick. Maybe because I am using a tapered bits but I do not get those nice little curly spiral DNA shapes like when I am drilling delrin. I think I am drilling at about 800 (Taig’s Slowest). The best defense is to use the rhythm method and pull it out, which I do frequently and the double drilling seems to extend the time the drill can CUT without getting too hot.
Last edited by ckr on Fri Jun 01, 2007 7:21 pm, edited 1 time in total.
Matt,
Long time no hear, glad to see you are back at it. You in love with that Taig or what?
Yea, it is not oil it is a blue water based solution, should have said fluid, Sorry, didn't mean to start a EPA investigation. However, I really don't think it would be a big issue. I figure after buffing the inner wall with compound and then scrubbing it out with a extra fluffy dipped in grain alcohol that an impermeable substance like cast acrylic would not have any residual fluid lingering. At least not that I can detect.
Long time no hear, glad to see you are back at it. You in love with that Taig or what?
Yea, it is not oil it is a blue water based solution, should have said fluid, Sorry, didn't mean to start a EPA investigation. However, I really don't think it would be a big issue. I figure after buffing the inner wall with compound and then scrubbing it out with a extra fluffy dipped in grain alcohol that an impermeable substance like cast acrylic would not have any residual fluid lingering. At least not that I can detect.
Last edited by ckr on Fri Jun 01, 2007 7:22 pm, edited 1 time in total.
Just my 2 cents worth, but 1200 rpm sounds way fast for drilling acrylic. Perhaps a slower speed & slower infeed might help a bit.
Somewhere in the dark recesses of my mind I think I recall reading somewhere that some "old hands" in the machining trade use(d) Crisco to lube acrylic when cutting & drilling. Give it a try, it's food grade, so it can't hurt. At worst, it'll taste like a french fry at first light up. LOL.
Somewhere in the dark recesses of my mind I think I recall reading somewhere that some "old hands" in the machining trade use(d) Crisco to lube acrylic when cutting & drilling. Give it a try, it's food grade, so it can't hurt. At worst, it'll taste like a french fry at first light up. LOL.
Regards,
Frank.
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Grouch Happens!
People usually get the gods they deserve - Terry Pratchett
Frank.
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Grouch Happens!
People usually get the gods they deserve - Terry Pratchett
it was suppose to be taken as an easily related to description of a prophylactic step I take not to impregnate the interior walls with any foreign matter. 
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staffwalker
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I apply the epoxy, get everything lined up the way I want it, put it in the vise and apply pressure which presses the excess epoxy into the draft hole. At this point I remove it from the vise, holding the parts together tightly so it can't shift and run three or four fluffy pipecleaners through the draft hole. I then reinsert into vise and clamp. I have used this method several times and I think it has failed once to the point I had to drill afterwards. I do the same thing when doing a delrin insert in a stem. The pipecleaners remove the excess so no drilling is needed.
bob gilbert
bob gilbert
I think the drill heats up as soon as it's cutting and rubbing the inside of the draft hole. I think it starts to over heat when the channels fill up and the heat has no where to go.ckr wrote:Hi Gunnar,
I use usually use delrin for my tenons, cuts like butter, no heat there at all. I do not think there would be much even if I did not double drill. I don’t think the drill heats up until the channels fill with material and the material rubs against the airway walls. Anyway, this is what appears to happen when drilling translucent acrylic. Even if it is five minute epoxy I do not usually drill to the next day. Most of my mistakes are from being in a hurry, so I make it a point not to be in a hurry.
On double drilling I think we are both experiencing the same benefits. One, being the only exposed epoxy is the seam where tenon meets the stem mortise. Two, cleaner cuts on the inside wall – although I can’t prove it with doing it on clear acrylic.
And hey, I am using cast!! I get a small flake type of shaving and they all bunch up eventually and jam up, then they get tighter and tighter until the start to rub the wall, heat and will stick. Maybe because I am using a tapered bits but I do not get those nice little curly spiral DNA shapes like when I am drilling delrin. I think I am drilling at about 800 (Taig’s Slowest). The best defense is to use the rhythm method and pull it out, which I do frequently and the double drilling seems to extend the time the drill can CUT without getting too hot.
I think you are drilling too slow. You're cutting very slow but not saving by generating substantially less heat. The acrylic is still getting plenty hot at 800 rpm or so. Try a faster speed and see if you can drill more with less pressure and hopefully not have things melting so much. Also make sure your bits are sharp enough. I would not be surprised if clear acrylic is of a different composition that just doesn't handle machining very well in-spite of being cast. I know different colors react differently.
Good post.
www.TotemStar.com - Some of my pipe related art
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KurtHuhn
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I've realized that acrylic stems are my arch-enemy. Especially anything even remotely clear. Every time I try one, I get about 1 material failure for each success.
The plastic pen blanks, however, are actually decent material, and hold up under heat and ressure a lot better than anything else I've used. No idea if that's acrylic or some other plastic though.
The plastic pen blanks, however, are actually decent material, and hold up under heat and ressure a lot better than anything else I've used. No idea if that's acrylic or some other plastic though.
Hey Kurt... I've often thought of using pen blanks in pipe making, but I haven't gotten to it yet.
What should I be aware of before turning or drilling?
Also, how does it respond to shaping/sanding? I've heard it is demanding to get all the
scratches out.
Any and all info would be much appreciated.
TIA
Steve Morrisette
What should I be aware of before turning or drilling?
Also, how does it respond to shaping/sanding? I've heard it is demanding to get all the
scratches out.
Any and all info would be much appreciated.
TIA
Steve Morrisette
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KurtHuhn
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- Location: United States/Rhode Island
Actually, it sands and polishes far easier than vulcanite. It drills without too much trouble, but not as easily as vulcanite. I haven't had a problem yet, and I've used quite a few over the years. It even bends well.
Problem is, I don't do too many pipes that need a stem with that many colors - otherwise I'd be using a lot more of them.
Problem is, I don't do too many pipes that need a stem with that many colors - otherwise I'd be using a lot more of them.