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No excuse not to make an er32 chuck for the lathe

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mickri

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I am just about finished with the tool holders for my norman style qctp and already realize that I am going to need more tool holders. Can you ever have too many?? I see an add on Craigslist for a company selling some 1018 crs 1 1/4" x 2" flat bar. Stop by and it is a CNC machine shop trying to sell their drops instead of sending them out for scrap value. Owner asked if there is anything else I could use and I mention 2" to 2 1/2" round bar. Takes me over to another rack and there is a 6" long piece of 2" round bar 1018 crs. That will work and he gives it to me no charge. They had a lot of other stuff that I can see would be useful for other projects down the road. And at less than $1 per lb fits nicely in my budget. The shop is in Visalia, CA. 1130 E. Acequia Street.

I now have the material. No excuse not to start making it.
 

hman

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Looks like you found a GREAT source. Congratulations!
 

Tozguy

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So howz it coming mickri? :)
Looking forward to seeing how you go about it.
 

mickri

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Hope to get started the middle of next week. Halligan142 has a nice video on making an er32 chuck for a lathe that I intend to follow. I have watched it so many times that I think I have it down. Have lots of other things that I need to get done too. I am going to finish the first batch of tool holders for my norman style qctp before starting another machining project. I will be using these tool holders to make the er32 chuck.
 

dtsh

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Having done this myself just recently with ER40, I found it quite handy. It's not 100% complete, but it's at a stage where it's usable. I used it today in fact to turn a brass bushing for my Brunton-style pocket transit. The making of the chuck was pretty straightforward. For getting the 8-degree taper just right, I set the compound as close to 8 degrees as I could and once I was close to size I kept checking the fit of a collet and tapping the compound between cuts until the dye on the collet showed full contact.
 

Tozguy

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dish, I did mine that way too. But it left me wondering if the collet taper changes as it tightens and whether we should allow for that.
 

Janderso

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I have a threaded spindle and the ER40 set.
I bought some 4” cast iron, “dura bar” for the mounting plate. The trick is to bore and cut the 1 7/8 8tpi internal thread.
Will be watching your project
 

rgray

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I usually set the compound with a sine bar for things like that.
Can be set off the extended tailstock ram, or better off a ground test bar between centers.
 

mickri

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This is how I intend to make the chuck. First I will figure out how long it needs to be and cut the work piece a little longer. Then I will drill/bore a hole, probably 3/4", all the way through. Next I will bore and thread one end to fit the 1 1/2 x 8 tpi on the spindle. I will then mount my mt2 er32 chuck in the spindle and set the compound to match the taper. Then the work piece gets screwed onto the spindle and I will cut the taper. Last will be cutting the external threads for the collet nut. This is just my general outline of the process. I didn't include every little step.
 

mattthemuppet2

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that place sounds like a great find! Next time you're there, ask if they have some 2" or larger hex bar, then you can make an ER32 collet block. Super handy things. I made an ER25 collet chuck for my Atlas 618 out of hex and I've used the "hex" aspect of it on the mill way more than I expected. Even drilling 2 holes in a rod 180deg from each other is made so much easier with it. Plus I didn't need to mill flats for a spanner :)
 

BaronJ

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dish, I did mine that way too. But it left me wondering if the collet taper changes as it tightens and whether we should allow for that.
No ! The collet taper does not change when tightening, only the bore diameter will alter to grip the workpiece.
 

mickri

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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.
 

mickri

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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?
 

BaronJ

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Hi Mick,

Yes that horizontal flat area behind the threads is where you want the best possible fit. The threads only hold the chuck on, its the register that sets the location.
 

mickri

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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.

IMG_3641.JPG

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.

IMG_3639.JPG

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.

IMG_3640.JPG

This is as far as I have gotten so far.
 

mickri

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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.

IMG_3643.JPG

Next I set the boring bar to center. I had previously made a mark on my trusty framing square for the center height.

IMG_3642.JPG

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.

IMG_3646.JPG

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.

IMG_3647.JPG

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.

IMG_3645.JPG

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.
 

mickri

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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.

IMG_3648.JPG

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.

IMG_3649.JPG

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.

IMG_3650.JPG

To test the fit I used a plate with 1 1/2 x 8 tpi that came with my lathe.

IMG_3572.JPG

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.
 

Tozguy

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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.
 

BaronJ

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Hi Mick,

Just use a piece of emery cloth on a bit of wooden dowel to knock the tops off the threads.
Then test fit again. It should be all right.
 

mickri

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The spindle end is done. It screws on easily and mates up square to the spindle. Before I took it out of the 4 jaw I used the jaws on the 4 jaw to scribe 4 lines to give me a reference to drill 4 holes around the chuck to help remove the chuck.

IMG_3652.JPG

IMG_3651.JPG

IMG_3653.JPG
 

mickri

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Next task is to drill some holes through or in the chuck so I can insert something in the chuck to be able to remove it from the spindle. Or I could use a strap wrench. Or I could mill two flats 180 degrees apart for a wrench. A hole for a bar seems to be the simplest solution. Would a 1/4" bar be big enough? I think the largest bar would be 3/8." Should the hole go all the way through? The chuck is 2 1/2" long. The spindle threads go in 1" and the collet goes in 1". This only leaves 1/2" in the middle for a bar to fit all the way through.

More decisions. Help me out.
 

Tozguy

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I think that you will need a wrench on the chuck to tighten the collet as well as to remove it from the spindle. If there is work extending through the chuck then a bar will not work. Might as well buy or make a pin wrench. I would hesitate to mill flats on the chuck for a spanner but that is just me.
 

BaronJ

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Hi Guys, Mick,

My personal preference would be spanner flats ! I don't think a 1/4" bar would be enough, and 3/8" would need a deeper hole than 1/4" to prevent pull over and hole damage.
Apart from removing the chuck from the spindle, tightening the collet, unless you have a ball bearing one, takes quite a fair amount of force.
 

mickri

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I decided against milling flats because I don't have a wrench big enough. So I drilled four 7/32 holes equally spaced around the chuck and have ordered another ER32 nut wrench that with just a bit of file work on the corners will fit in the holes. And I have faced off the collet end of the chuck.

Next task is to bore a tapered hole for the collets to fit into. I set my compound at 8 degrees as a starting point. I put an ER32 / mt2 chuck into the spindle which I am using to more precisely set the taper. Here is my setup.

IMG_3656.JPG

I have to read the TDI with a mirror. I set the height of the probe on the TDI at center height. My TDI has .0001 printed on the face and the range goes from 0 to 15 then back to 0. My current range of movement is from 0 to 5 on the dial which I believe is .0005 if I am reading the TDI correctly. I have tried gently tapping the compound to try to obtain a smaller range with no success. Is this close enough? Suggestions please.
 

BaronJ

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Hi Mick,

Yes each division is 1 tenth. Why don't you just turn the TDI through 180 degrees then you can see the face properly. The stylus can be moved if need be.
 

mickri

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Well I tried again this morning with the same result. No matter what I try I always get a range of movement of .0005. At this point my conclusion is that .0005 is the tolerance in the chuck. And I was able to turn the TDI 180 degrees. Same result. Have to go to town today. Will cut the taper tomorrow.
 

BaronJ

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Hi Mick,

Half a thou isn't to be sniffed at. However there are lots of places that can move to show that tiny amount. If you think that its the spindle, then use a long wooden batten to lever the spindle up or to the side with the DTI in the bore. It will soon show how much the spindle will affect your readings.

Though I would want to greatly reduce the distance between the mag stand and the DTI, since a half thou indicator on a long arm like you show would influence the readings you are getting. I try and make my setup as rigid as I can.

13-09-2018-18.JPG
This is the setup that I use to make measurements similar to the one that you are making.
This replaces the lathe tool in the holder. I can replace the gauge with any of the ones that I have.
 

ericc

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Not able to indicate a constant taper? Maybe the chuck is not to blame. If you are off center, but parallel to the axis, the indicator tip traces a hyperbola, which does not have a constant slope. The needle will always be moving. This makes a good interview question. A perfect taper is just a truncated cone, whose equation is very simple in rectangular-cylindircal coordinates. Solve the equation of the intersection of this shape and any z-plane. You only get a straight line at the origin. All the rest are hyperbolas.
 
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