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No ! The collet taper does not change when tightening, only the bore diameter will alter to grip the workpiece.
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No excuse not to make an er32 chuck for the lathe
- Thread starter mickri
- Start date
No ! The collet taper does not change when tightening, only the bore diameter will alter to grip the workpiece.
- Joined
- Oct 31, 2016
- Messages
- 2,721
Got started today. I cut the 2" OD round bar to length this morning. That was fun with a hacksaw. Took awhile. This afternoon I was able to face off the rough cut from the hacksaw and got the center hole drilled to my largest drill which is 3/4." Hoping to start Monday boring the center hole to its finished ID of 1" and then bore the headstock end to the minor diameter of the 1 1/2 x 8 tpi. That's the progress so far.
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- Oct 31, 2016
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Looked up the minor diameter. The range is 1.365" to 1.390." Since I tend to be oversize on the holes that I bore I will shoot for the 1.365 which should keep me within the range of minor diameters. In the Halligan142 video he said to make the thread a little sloppy on the fit because the chuck should seat on spindle and not on the threads. Is this correct?
- Joined
- Oct 31, 2016
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Here are some pictures. I have a Jacobs chuck that fits on my spindle. I am using it as a guide.
I measured the inside diameter of my mt2 er32 chuck and it is 25 mm. I have bored a hole all the way through about .040 undersize. This gives me a little wiggle room when it comes time to bore the taper for the collets.
Back to the spindle end. The minor diameter for a 1 1/2 x 8 tpi is 1.365 to 1.390. My Jacobs spindle chuck has a minor diameter of 1.385. To give me a visual on boring the hole to the minor diameter I put some dykem on the end of the work and then scribed a line at a minor diameter of 1.365. You can barely see the line in the picture.
Because the minor diameter for the threads is greater than the through hole I was concerned about the end of the boring bar hitting against the shoulder. Using the scribed line as a guide I extended the tool bit so that the boring bar would not hit up against the shoulder. The tool bit now extends slightly past the end of the boring bar.
This is as far as I have gotten so far.
I measured the inside diameter of my mt2 er32 chuck and it is 25 mm. I have bored a hole all the way through about .040 undersize. This gives me a little wiggle room when it comes time to bore the taper for the collets.
Back to the spindle end. The minor diameter for a 1 1/2 x 8 tpi is 1.365 to 1.390. My Jacobs spindle chuck has a minor diameter of 1.385. To give me a visual on boring the hole to the minor diameter I put some dykem on the end of the work and then scribed a line at a minor diameter of 1.365. You can barely see the line in the picture.
Because the minor diameter for the threads is greater than the through hole I was concerned about the end of the boring bar hitting against the shoulder. Using the scribed line as a guide I extended the tool bit so that the boring bar would not hit up against the shoulder. The tool bit now extends slightly past the end of the boring bar.
This is as far as I have gotten so far.
- Joined
- Oct 31, 2016
- Messages
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Some more set up pictures. Going off my guide the depth of the cut for the spindle threads is 1.1" I put some dykem on the work and made a mark 1.1" in.
Next I set the boring bar to center. I had previously made a mark on my trusty framing square for the center height.
and aligned the boring bar to the lathe. In this case I had used the tailstock ram to align the boring bar to bore the center through hole and to keep everything apples to apples I used the the tailstock ram again.
Next was to set the stop for the depth of the bore. Remember the mark I had made. I aligned the tip of the baring bar with the mark and locked the carriage in place.
I now adjusted the carriage stop. I don't have a set up yet to use a dial indicator. I have found that putting a piece of paper between the stop and the carriage allows me to feel when the carriage just touches the stop. When I can't move the paper I know the carriage is at the stop and I disengage the half nuts. It works for me.
I will go over everything again before I start to bore for the minor diameter of the threads just in case I made an error somewhere. The old measure twice cut once theory. It usually works for me.
Next I set the boring bar to center. I had previously made a mark on my trusty framing square for the center height.
and aligned the boring bar to the lathe. In this case I had used the tailstock ram to align the boring bar to bore the center through hole and to keep everything apples to apples I used the the tailstock ram again.
Next was to set the stop for the depth of the bore. Remember the mark I had made. I aligned the tip of the baring bar with the mark and locked the carriage in place.
I now adjusted the carriage stop. I don't have a set up yet to use a dial indicator. I have found that putting a piece of paper between the stop and the carriage allows me to feel when the carriage just touches the stop. When I can't move the paper I know the carriage is at the stop and I disengage the half nuts. It works for me.
I will go over everything again before I start to bore for the minor diameter of the threads just in case I made an error somewhere. The old measure twice cut once theory. It usually works for me.
- Joined
- Oct 31, 2016
- Messages
- 2,721
More progress. This morning I got the spindle end bored out to the minor diameter. The mark I made turned out to be spot on.
Next I tried to cut a thread relief groove. I ground a tool like I had posted on Mikey's tool model thread and set it to depth using the depth mark I had previous scratched on the side of the work.
But it just wouldn't cut the thread relief no matter what I tried. I changed the angles a bit. I honed the tool bit. I tried it on center, just above and just below. Nothing worked. So I gave up on the thread relief groove and cut the thread. The cut thread does not show up well in the picture. Too much glare.
To test the fit I used a plate with 1 1/2 x 8 tpi that came with my lathe.
The plate is a very smooth fit on the threads. It easily screws into the er32 chuck but it is not sloppy. When screwed all the way on the plate seats up solid against the er32 chuck. The question is should I make another pass to loosen up the threads in the er32 chuck? Or leave it as is. I don't wanted to remove the er32 chuck from the 4 jaw or cut the relief for the spindle until I am done with the threading.
Suggestions please.
Next I tried to cut a thread relief groove. I ground a tool like I had posted on Mikey's tool model thread and set it to depth using the depth mark I had previous scratched on the side of the work.
But it just wouldn't cut the thread relief no matter what I tried. I changed the angles a bit. I honed the tool bit. I tried it on center, just above and just below. Nothing worked. So I gave up on the thread relief groove and cut the thread. The cut thread does not show up well in the picture. Too much glare.
To test the fit I used a plate with 1 1/2 x 8 tpi that came with my lathe.
The plate is a very smooth fit on the threads. It easily screws into the er32 chuck but it is not sloppy. When screwed all the way on the plate seats up solid against the er32 chuck. The question is should I make another pass to loosen up the threads in the er32 chuck? Or leave it as is. I don't wanted to remove the er32 chuck from the 4 jaw or cut the relief for the spindle until I am done with the threading.
Suggestions please.
Do you know how close the test thread is in size to your spindle threads? It sounds like a good fit to the test threads but the spindle thread would have to be identical or smaller. If not then you could always chuck the ER chuck back up in the 4 jaw and pick up the threads.