Drill fixture for lathe

[Janger]

Well we seem to have lost some content due to the server crash. The ones I’ve noticed we had a ELS thread, a C0636 & other 14x40 lathe thread and this thread to get going again.

I’m working a drill fixture for lathes to allow holes offset from the Center axis. Pics….

 

[Janger]

Pics .. with drill model I found on a CAD forum.

 

[Janger]

A picture of the result. It is working. The drill is held pretty solid by just the front clamp so I don't even need the supports on the drill body. One disappointment is the drill bearings have some slop so the chuck wiggles reducing accuracy - perhaps by +/- 0.010" or 0.020". It is just a hand drill. I've successfully drilled a 3 hole pattern for a flange as a test. This will be useful for the occasional hole required off center. Especially when the part is long and won't fit in the mill (like a lead screw). I'll try to post more pictures when the forum supports large image files again.

 

[Janger]

ok from the front.

 

[Janger]

Now I'm going to try to drill a starting hole every 15 degrees with my silly Ikea tape measure angle guide.

 

[Janger]

Hmm results. I had to go with 30 degrees too tight for 15. Where I’m pointing is off a bit. Checking the numbers I think the circumference is actually 378.1mm not 379.1mm. So the last hole should have been at 362.3mm instead of 363.3mm. One or two other holes look a bit wonky. I probably missed aligning the spindle to the tape…

 

[Janger]

I’ve ordered a foot pedal for the drill power too.

 

[Janger]

Well the mitutoyo big caliper says the spindle is 117.3mm in diameter which is 368.5mm in circumference. Ikea thinks it is 378.1mm. That's a lot almost 1cm. I No no no. Wrong reading it wrong. Ikea says 368.2. I'm asking a lot of a free plastic tape measure! :> That's actually pretty close!

I am going to have to regroup. This needs more thought.

I could mount the rotary table to the chuck and position the spindle at specific degrees on the clock and mark the spindle perhaps. How do people do this?

 

[Janger]

Now that I'm reading right... doh! ... I'll try this again. I drilled the last hole at 345 degrees at 363.3mm in circumference - it should be 352.9. which probably explains the wonky drill pattern.

 

[YYCHM]

Well the mitutoyo big caliper says the spindle is 117.3mm in diameter which is 368.5mm in circumference. Ikea thinks it is 378.1mm. That's a lot almost 1cm. I No no no. Wrong reading it wrong. Ikea says 368.2. I'm asking a lot of a free plastic tape measure! :> That's actually pretty close!

I am going to have to regroup. This needs more thought.

I could mount the rotary table to the chuck and position the spindle at specific degrees on the clock and mark the spindle perhaps. How do people do this?

You lost me..... What are you trying to do?

 

[Janger]

Ah! Right Craig I’m not being too clear. I’m trying to rotate the lathe spindle in 30 degree increments to make a bolt round pattern on a round part. Like this.

 

[YYCHM]

Ah! Right Craig I’m not being too clear. I’m trying to rotate the lathe spindle in 30 degree increments to make a bolt round pattern on a round part. Like this.

PA timing degree wheel

PA Calgary North has two still. Makes a nice lathe indexer. https://www.princessauto.com/en/detail/timing-degree-wheel/A-p8514721e

canadianhobbymetalworkers.com

This is an indexer I made for my mini-lathe...



That's a 120 tooth gear from PMS Hobbies, so 3 deg increments.

 

[PaulL]

Ah! Right Craig I’m not being too clear. I’m trying to rotate the lathe spindle in 30 degree increments to make a bolt round pattern on a round part. Like this.

My little indexing jig has an unfortunate amount of backlash that I have to take out pretty carefully every time I move the index (yes, I need to remake my spindle now that I'm a bit better at this machining thing).

Could it be something as simple?

 

[Janger]

I'm going to follow Craig and 3D print a plastic indexer. maybe with 15 degree index holes. 3 degree notches. 1 degree marks?

 

[DPittman]

On my little lathe I made a disc with a printed degree (or numered) label that attaches into the back of spindle hole with a expanding tapered plug. I then just use a simple pointing needle in a magnetic stand to indicate my position. The bigger wheel/disc you have the more potential accuracy it can have. My disc is an old vinyl LP (Blue Oyster Cult Club... cuz that matters). The only thing I haven't been able to incorporate yet is a locking mechanism to hold the spindle from moving. However if I am carefull it seems to work surprisingly well without. I've cut a few small gears on my lathe with it and indexed a few items.

 

[Janger]

More pics
Yay Josh fixed the picture upload!

 

[Janger]

Replaced ikea nonsense with plastic nonesense!

 

[Janger]

Actually the plastic ring part works pretty good. The piece to hold the indexing pin is way too flimsy - needs to be metal or printed thicker and denser. I think a threaded pin would work well.

 

[Susquatch]

Actually the plastic ring part works pretty good. The piece to hold the indexing pin is way too flimsy - needs to be metal or printed thicker and denser. I think a threaded pin would work well.

Why is the pin even needed? Isn't your indexing mark sufficient?

 

[Susquatch]

Actually the plastic ring part works pretty good. The piece to hold the indexing pin is way too flimsy - needs to be metal or printed thicker and denser. I think a threaded pin would work well.

Further to that, you could even make a sort of vernier scale at the indexing mark and use that to align the spindle.

I doubt the pin could ever stop the spindle from turning. Just put the lathe in your lowest gear, turn and index the spindle using the motor belt, and put a stop cog in the lead screw gears. Just don't forget to remove it.