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| Just finished my QCTP. |
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| websterz:
Nothing new under the sun, but here's my take on the QCTP anyway. I started out with a 2" cube of 12L14 which turned into the post body. The cam is a piece of 303 stainless round I had knocking around the shop, and the center post is 3/4" drill rod. 1/4" drill rod was used for the handle, and 1/2" for the 2 pistons. Here it is all fitted together: Here is a view showing the parts spread out a bit: My solution to the problem of keeping the pistons from falling out is shown here. I drilled holes up from the underside of the body that bisect the piston holes. 8-32 setscrews hold short lengths of 1/8" drill rod in place. Each piston is cross drilled with a 3/16" hole to allow it plenty of movement while still being trapped in the hole by the pin: The tool holder shown is just a quick test piece I made from a scrap of 7075 so I could check the function of the post. Future holders will be made from steel for extra mass and rigidity. A test with the parting tool shows the setup to be extremely rigid. I am a happy camper. It took me 3 days of on and off work to build, probably 10-12 hours total. I apologize for the less-than-stellar pics. My wife has the camera in her car and I was forced to use my cell. :doh: I will get some video of it later on this week (if I get my camera back that is :D). |
| jamoni:
So the cam was turned with an eccentric, right? Are all the sliding surfaces hardened? |
| websterz:
--- Quote from: jamoni on January 14, 2010, 09:46:16 PM ---So the cam was turned with an eccentric, right? Are all the sliding surfaces hardened? --- End quote --- I did all the lathe work in my 4 jaw chuck. I didn't measure the cam offset, I fly by the seat of my pants a lot. :dremel: Checking it just now there looks to be about .048" offset. I don't plan to harden the post...12L14 probably won't respond too well to heat treatment. This goes on my 7x12 lathe so it's not a high use production environment. :D It will likely outlive the lathe. One change I may make is to replace the 1/2" round pistons with rectangular ones (or at least larger round ones) for better contact. If the tool holder's not fairly centered it wants to cant a bit when I lock it down. |
| Bernd:
Nice fly-by-the-seat tooling. :thumbup: I've always figured it was complicated making one of those holders. I do have one on my Logan, but need more holders for it. In order to make those I need a dovetail cutter. Just to many excuses to use for procrastination on making one. Perhaps on the next tool order. :poke: Bernd |
| NickG:
Nice work Websterz. This is on my list of projects but keeps getting pushed down. It's still on there because I can't afford to buy one but different models keep jumping in the way! I think what's putting me off is the number of holders I'll need! :lol: Great job though. I can't see the need for hardening either really. Nick |
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