Well seeing this was your post to start with, why don't you tell us what you found and become part of the solution instead of just the question.
drilling and tapping shaft holes accurately
- Thread starter kiinstructor
- Start date
Wild guess; use wax, backing-off after one revolution of the chuck, blow air in the hole, then go forward one revolution?
JoeyInCali said:
Yeah, good point, the air is important, If one does'nt blow the shavings out they can destroy the threads as they are being cut. Sometimes you can shoot the air through the reliefs in the tap and they will come out one of the opposite reliefs. I've used wax on 3/8 when they will be wood threads in the finished product, and it does help. Hardening the wood before cutting has also helped me cut cleaner threads before.
Well, heres what Im doing. First I had a heck of a time aligning my tailstock. Easy enough to align side to side but it had a tilt and it took some machining and indicating by a machinist friend of mine to get the thing right. Anyway what I do is drill a hole with a 1/4 inch carbide endmill that is short and stiff, could probably be any kind of carbide drill but the key is stiff. No Wandering. I drill the hole about 1 1/4 . My pin is about 1 1/8. Then I use a carbide boring bar and inlarge the hole to .2800. This is for a 3/8 10 pin. Then I set the shaft with the hole upright in my shaft cart and fill the hole with thin super glue and leave it for about 10 or 15 minutes. I want it to spill out and harden the outside of the hole also. Then I pour the glue out and let it dry overnight. I know this glue sets up fast but I think the soaking process is important and the curing time is important as I have tried it other ways and it doesnt work as well. Ive found that putting the shaft in front of a fan and letting it blow in there really dries it good. The next day I put the shaft back in the lathe and indicate it. Key here is to make sure the shaft is centered in the spindle. Back and front. I made a tap holder with a 1/4 inch jacobs chuck and drilled a pilot hole in back #2 Morese taper adapter to it holds the tap perfectly straight. I fill the front part of the hole with mothers wax. What I like about mothers is it doesnt discolor the wood . Then I put a little on the tip of the tap and run it up to the hole and with a live center in the tailstock I push it up to the pilot hole in the jacobs chuck and push the tap in slowly and tap by hand letting the tail stock slide as I go. I run it in about 3/4 of an inch and back it out and blow it out with air hose. Then a little more wax and I finish the tapping. Man the threads are perfect. Smooth and no chips. Also when I put a pin in and fire up the lathe, its true and can be. So, as I said earlier with the help I got from you guys and a little trial and error I found a solution. Happy tapping!Michael Webb said:
How are you tapping? Are you using the laethe or are you moving the chuck by hand. I had trouble with 3/8-10 also and found that I had to countersink the hole a little to get the tap started straight and turned the chuck by hand. Listening to some of these other guys tells me I was doing other things wrong also. I use radial, no problem. butterflycues
I dont use the lathe power to turn the tap. Its all hand power. Just follow the directions I listed before and you shouldnt have any problems .. No need to drill any other hole besides the .2800. The tap will center itself will light pressure from the tailstock. Just turn the tap by hand and it will cut the threads smoothly. Good luckbutterflycues said:
builder
Hi how are you? i thought i would give you a little input into what i have found out on tapping shaft,s. sometimes you can drill a perfect hole then tap it and it,s crooked it,s because the tap is pulling side way,s . the way to solve the problem is simple. first off get your shaft in perfect line from end to end before doing anything i alway,s drill and tap my holes why the shaft,s are larger putting a nice 60 degree center in them then drill and tap them and then turn the shaft,s down to size after words this insures the shaft is turned to the center you drilled off of .as i said get the shaft in good line from end to end then use a starter bit to bunch a center then go to a nice sharp bit that,s a a little smaller than the finished hole you want then drill to depth then bring the hole out to finished size with a boring bar now this is were your problem can start if you don,t do this take your boring bar and open the first part of the shaft hole about 200 thousands to 250 thousands in bringing it out to the outside dia. of the tap this allows the tap to go into the hole striaght aligning it for a perfect tap everytime this is the same as grinding your tap like the radial tap is done but your just doing it to the shaft instead . i bet your holes are drilled striaght it,s just the tap pulling side way,s try this and you,ll see great result,s everytime. THANKS BUILDER BOB
Hi how are you? i thought i would give you a little input into what i have found out on tapping shaft,s. sometimes you can drill a perfect hole then tap it and it,s crooked it,s because the tap is pulling side way,s . the way to solve the problem is simple. first off get your shaft in perfect line from end to end before doing anything i alway,s drill and tap my holes why the shaft,s are larger putting a nice 60 degree center in them then drill and tap them and then turn the shaft,s down to size after words this insures the shaft is turned to the center you drilled off of .as i said get the shaft in good line from end to end then use a starter bit to bunch a center then go to a nice sharp bit that,s a a little smaller than the finished hole you want then drill to depth then bring the hole out to finished size with a boring bar now this is were your problem can start if you don,t do this take your boring bar and open the first part of the shaft hole about 200 thousands to 250 thousands in bringing it out to the outside dia. of the tap this allows the tap to go into the hole striaght aligning it for a perfect tap everytime this is the same as grinding your tap like the radial tap is done but your just doing it to the shaft instead . i bet your holes are drilled striaght it,s just the tap pulling side way,s try this and you,ll see great result,s everytime. THANKS BUILDER BOB
Hi Bob, Thanks for the input. Im learning more and more. Im a little confused on boring this starting hole. What are you using for a 60 degree starter hole to turn your oversized shafts with?. A #5 starter bit or what? Second Ive got a hole drilled straight to .2800. then what? My pins are approx. 3/8 OD. How deep do you bore this starter hole and how large should it be. Thanks a bunch.bob griffin said:
madison bob
Hi how are you? i use a 5 1/16 starter bit going in all the way to the end of the 60 degree center then i pull out and go to a 0.292 bit drill then measusure your pin length and add 0.350 to the depth because if you notice on your tap it is tapered and does not tap all the way to the bottom of the hole so add this amount to the depth are a little more to be on the safe side since tap,s do differ some in these area,s. then mark your bit and drill to the proper depth. know change over to a boring bar and open up the hole the full length of the hole you drilled to 0.312 again this vary,s do to pin,s and tap,s but this is a good reference point you should measure the inside threads of your tap and pin to get this number but this is what mine measure. now take a 3/4 starter bit which as a 0.312 dia. drill on the end that will slide right in to the hole you just bored and go in untill you have a 1/2 dia. 60 degree center to turn your shaft off of that,s now in perfect alignment with your hole you bored. Then here,s what keep,s you striaght when tapping any hole take your boring bar and now bore in 0.200 to 0.250 deep this should be the same as the outside dia. of your pin are tap which in my case would be 0.372 inch dia. clean any burr,s up from around hole . now change to your tap slowly and firmly push it in to the hole and turn in a way,s then back out a little not all the way out then go in a little more and back out do this untill the hole is tapped to the bottom then reverse the lathe are just back it out by hand blow out hole and your done. if you want to tighten up the fit to the pin you can now take a water based clearcoat and take a eye droper and fill the hole of the shaft removing it with a vacuam quickly if you leave it in there very long it will make it really tight fitting so move fast once the clear dry,s it will give the shaft really nice fitting threads that will last for the life time of the cue if you need to you can get on my sight and get my number and call me www.madisonbobs.com and i,ll walk you thru this it,s hard to cover everything in this reply and i,am sure not everyone will agree with this method but i have done this for ever and it work,s everytime for me i hope it help,s !! THANK,S MADISON BOB ps. forgot to mention get your shaft,s running as true as you can from end to end this doe,s not mean with 2 chuck,s one on the front of the lathe and one on the back because then your forceing the shaft to run true and when you then get done quess what the hole is crooked. I float them by hand as the lathe is running untill it look,s striaght then i indicate it in and i have a tailstock in the rear of my lathe mounted on a piece of dove tail that,s in perfect alignment with the center of my spindle that way i can see most of the shaft as it,s running in the lathe and then i know the shaft is not being forced at any time to run striaght. I also have a way to install 3/8x10 pin,s in the butt that will make them run perfect everytime useing a pilot hole and only taping about 3/4 to 1inch of the butt at the bottom of the hole the rest of the hole is used to align the pin and offer glue relief giving a perfect alignment and solid install everytimekiinstructor said:
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