# Another version of a D1-4 ER40 Set-Tru (adjustable) chuck



## mksj (Oct 4, 2017)

This is another variation on making and ER40 adjustable Set-Tru chuck, taking some design hints from those previously posted.
http://www.hobby-machinist.com/threads/er40-adjust-true-collet-chuck-for-d1-4-camlock.61808/
http://www.hobby-machinist.com/threads/building-a-set-true-er-40-collet-chuck.62089/

There is no marketed set true (Set-Tru)  ER chucks, and the direct mount ER chucks are not very well made and have limited reach away from their mount (short).

Although I primarily use a 5C Set-Tru collet system, there have been occasions were their limited clamping range has been an issue especially with odd size materials or metric stock. I had used an ER-32 system on my previous mill and currently use an R-8  ER40 chuck for larger end mills, and a MT3 ER40  chuck in the tailstock of my lathe. Comes in really handy for using end mills to square up smaller holes in the lathe.  My ER40 collet set is in 1/32 increments from 0.125" - 1.125".

I had previously ordered the D1-4 direct mount ER40 chuck from HHIP, and the run out was pretty bad (10X worse than specified), as well as its collet angular alignment was  poor.  It was returned a long time ago.
So recently I decided to make a Set-Tru  ER40 chuck that was very similar to my Bison 5C Set-Tru chuck dimensions (125mm back plate, overall length is 4.25"). I decided to purchase a Set-Tru  D1-4 back plate as well as the dog point allen screws. The dog point allen screws are very fine thread, M12 - 1.0  so I also needed to order in a tap. I purchase a TMX (polish) tap ($10), you can purchase  Chinese generic taps for less  but the reviews were pretty bad. I have used TMX taps previously, they have worked great and are very reasonably priced.

The Set-Tru back plate is a Gator  FLA-125D4, and the Gator adjustment screws FS-P-125 that  I purchased them from Ajax Industries. Total price was around $150 shipped, these are the exact same dimensions as the Bison counterparts, but 1/3rd the price. I decided to make the chuck body out of hot rolled 8620 alloy steel but also considered a 4130/4140 alloy depending on what I could find/purchase inexpensively. I have turned/machined 10XX steels, really do not like their machinability, nor their finish.   I purchased two 5" rounds x 4.5" of 8620 for ~$40 including shipping. I thought it would be wise to get two pieces, just in case the first round did not work out. Good size chunks of steel, about 35 lbs each, and I would end up turning down about 2/3rds of the material.



I had to give some thought as to the sequencing of steps so you minimize tolerance errors and have the clearances to machine the next step.   I started out mounting the rough stock in my 8" 4J independent, as it had the widest jaws to grab the round stock which was very uneven. I then faced the end and took a skim cut to true up the diameter. I then center drilled the round stock  to 1.0" and then center bored to 1.250". I then cut the registration step for the Set-Tru back plate step. Since very little adjustment is needed the  FLA-125D4 step "C" is specified at 2.165" and I cut the chuck to registration step to 2.175" which gave me a 0.005" adjustment from center. I was also thinking of adding a stop system for the ER40 chuck, so the I cut an internal 1.25-20 female thread to except a 5C collet screwed into the back. This provides a guide for longer stock, but I will eventually make a stop system with a through spindle bar that will allow both coarse and fine position adjust from the spider end.








I then flipped the round stock  and cut the outer chuck body dimensions to within 0.1" of their final dimensions (which are all metric). I only used a live center to apply pressure on the rough stock to hold it in place, not to center it. The plan was that all the final dimensioning would be done with the chuck mounted to the back plate.  So far all the tolerances were kept under 0.001".  The chuck body needed to be rough cut down so the chuck mounting holes could be drilled, the mounting holes were done on the mill using the bolt circle program (love those programs). Mounting screws are three M10 - 1.5  x 40mm allen bolts. The chuck mounting holes are 11.0mm to allow some movement, the head recess  was cut with a 9/16" end mill.




The rough chuck was then mounted to the Set-Tru back plate, I cut a strip of 0.005" brass shim stock to fit in the registration  step to center the chuck (I did not have the M12-1.0 tap at this time, otherwise they could have been used to center the chuck). I then recut the whole chuck to its final dimensions. The next step was cutting the metric M50 - 1.5  ER40 thread. Given the amount of time in getting to this point, it is easy to blow it on cutting this thread, in particular with a steel I had not used before. In hindsight, I should have gotten some 2" 8620 stock and practiced on that first to figure out the cutter/speed and depth. Since I use a proximity stop system, I do not have any issues with the stop position and the half-nut always remains engaged until the thread is completed. The issue I did have, was twofold, I started out with a positive rake thread insert cutter and the 8620 does not cut well with this type of cutter. The second problem is that when using the cross slide to cut the thread depth, one needs to take lighter cuts. On one pass, I took a bit too much of a cut with a positive rake threading insert and it blow it apart. Went back to a neutral rake insert and shallower cuts. The thread came out ok, but not a perfect thread, so I should have done a test run. Lesson learned.

The next step was cutting the collet 8 degree bevel, this proved to be a bit easier than I thought. I mounted my R-8 ER40  chuck in a 4J chuck and centered it, I then used a 0.0001" test indicator to sweep the bevel and adjusted the cross slide until the start/end of the sweep showed almost no deviation on the test indicator. I then used a 3/4" boring bar to cut the bevel until the collet depth in the chuck matched my other ER40 chucks. If I had some hi spot dye I would have used that to verify the angle initially, I used the old magic marker and looked at the rub patterns. This needs to be done with round bar stock in the collet, otherwise the collet will unevenly deform and you will not get a true representation of the collet seating. I also used a ball bearing ER40 collet nut, this significantly improved both the repeatability and measure runout.




The final step was to drill the Set-Tru allen bolt holes and tap them, and cut the hex key to lock the chuck relative to the ER40 nut.  I mounted a 1" precision ground bar in the ER40 chuck and then mounted the bar to a 5C square block. This was setup in the mill, I used a 90 degree angle block to set the back face of the chuck (and clamped it to the angle block), the collet block was then indexed in the vise at 90 degree increments. These holes must not interfere with the chuck mounting holes.  Alternatively I could have mounted the whole thing to my rotary table, which I should have done, but it is so darn heavy I got lazy. The collet blocked worked ok, just make sure it is locked very tightly. I should have used the rotary table. My R-8 ER40 chuck uses a 46mm wrench to hold the chuck, the wrench I use is for automobiles and has a narrow width profile (0.230"). I used a hex collet block and cut the 46mm hex on the chuck neck using a 4F 0.25" end mill.  The system works very well and easy, since both keys are close together.






So when completed I mounted everything up, adjusted the Set-Tru allen bolts and was able to get a repeatable TIR of 0.0001" at the chuck head was and ~0.0004" on a 1" stock at 4" out. Actually does better than my Bison 5C Set-Tru. The ER40 collets usually have less runout in comparison to 5C collets, and also the contact holding area is much greater.  That being said the Lyndex 5C collets all measure very well.


----------



## T Bredehoft (Oct 4, 2017)

Nice write up/illustrations. My Clausing MK2 isn't capable of lots of things, including D1 chuck mounting. If I had a real lathe I'd make what you did. Having the equipment I have, I tried twice unsuccessfully to make an ER 40 chuck, then found on-line a ER 40 chuck with an M 2 taper, just the thing for my toy lathe. a backup ring screwed on the spindle and a draw bar gave me a satisfactory substitute.


----------



## darkzero (Oct 4, 2017)

Nice, I like how you designed yours. Great job!


----------



## Bob Korves (Oct 4, 2017)

Very nice work and equally nice documentation of it!  It will be copied...


----------



## Alan H. (Oct 4, 2017)

Fantastic job Mark.  Your usual top shelf work! 

As always, you are giving back to this community.  I have taken advantage of many of your ideas and copied them shamelessly.  Once again, thanks for sharing.


----------



## Bamban (Oct 4, 2017)

Mark,

Nicely done. I have an Asian 5C adjustable chuck with about 20 Lyndex collets that I never used due to excessive runout. Maybe sometime next year I may tackle one like yours. I like ER collets have chucks on every machine, just 32 though.

Runout on your project is enviable.


----------



## Firestopper (Oct 5, 2017)

Mark,

Excellent work as always and a enjoyable read as well. 
Since your rotary table is too heavy and a PITA to set up, you should sell it to me  hahaha.
Seriously, great work brother.

Paco


----------



## [X]Outlaw (Oct 9, 2017)

Excellent work Mark and great write up!


----------

