Author Topic: Making a 201 toolholder and learning a new threading method  (Read 1685 times)

Offline Joco

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Making a 201 toolholder and learning a new threading method
« on: December 31, 2017, 04:35:13 AM »
Over the last number of days I've been slowly working on another toolholder for the QCTP and while doing it I decided to make use of the setups to make a number of the sub parts for later .i.e. multiple M10x1 rods and the height/locking wheels.  I also delved into the use of the "Method 3" as described in "Screw Cutting in the Lathe" by Martin Cleeve on page 139. In this method the topslide is parallel to the ways, not at 29.5 degs (assuming a 60 deg thread form). In this method you achieve the same diagonal tracking of the tool tip by moving the topslide half of the cross slide movement.  The main advantage I can see is that it is easy to get to the correct depth via the cross slide then you can, if needed, thin the thread by moving the topslide a couple of 100ths of a mm at a time.
 
The game plan is to make a holder pretty much to this plan.

 
So some pics ...

The blank roughed out ready to use dovetail cutter on.


Some blanks ready for further work.   Wheels tapped M10x1 and the threaded rods cut M10x1 using the "Method 3" I talked about at the start of this post.


The wheels mounted on a threaded rod and held in an ER32 collet on the mill.  The block of the holder is a hex so you a pretty simple exercise of getting the depth of cut lined up (using an 8mm end mill and 1mm depth of cut from the edge of the circle) and just keep rotating the block in the vice until all the little half moons are cut out.


The end result with a completed toolholder and my last tool without a home mounted in it. The M8 cap screws have been shortened in the lathe and the ends make nice an flat and chamfered.  The threaded rod has had a flat milled on the blank head.  The rsult in an effective 8mm nut for locking the shaft in nice and tight into the toolholder base.  No loctite really needed here as there is no load on this part of the tool.




The extra parts that were made and in their sub assembly ready for three more toolholders to be made.


Cheers,
James.
James
Wellington - NZ

Online Kim

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Re: Making a 201 toolholder and learning a new threading method
« Reply #1 on: December 31, 2017, 06:08:56 AM »
Looks like a first rate job on those tool holders!
Kim

Offline 10KPete

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Re: Making a 201 toolholder and learning a new threading method
« Reply #2 on: December 31, 2017, 07:00:23 AM »
Nice work. I suspect you'll make more than three more... :o

How much trouble was it to fit the dovetail or did you do the adjustments right in the mill? As opposed to hand fitting. I've never played around with the required tolerances 'cause I've never made a dovetail for my tool post!! :embarassed:

Thanks,
Pete
Craftsman, Tinkerer, Curious Person.
Retired, finally!
SB 10K lathe, Benchmaster mill. And stuff.

Offline Joco

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Re: Making a 201 toolholder and learning a new threading method
« Reply #3 on: December 31, 2017, 07:41:14 AM »
Kim - thanks!

Pete - the plans are based on the commercial holders I have that fit the tool post.  I have tightened up the tolerances a little since I'm not making these for anyone else.

My order of operation is to mill out the 35mm primary gap then bring in the dovetail cutter.  It's a HSS cutter from AliExpress.  At $10 landed for a 20mm diameter cutter its pretty hard to beat.  Back on point, Blue the side walls and base of the cut out then align dovetail to the ground and just touching one wall. Cut that side back and forth going in 4.72 to 4.75mm.  No more.  Move to the other side and do the same  but stop at 4.7mm and measure the dovetail with pins.  Measure an existing "good" holder and compare.  Take some more off the 4.7mm depth side (in about 0.05mm increments) until a close but comfortable fit.   It might not be the fastest but it works for me.  See these pics:





This particular instance (my first ever attempt) was a little large so I took to it with my very new/early TIG Brazing skills and piled a whole heap of silicon bronze to build it back up again. Was about the second time I had even used silicone bronze.


Then remachined up and it fits like a glove and is now the toolholder for my threading tool.


In all honesty once you get into the method that works for you its pretty straight forward.  Unless you have a Myford tool post which has all those funny angles and sections.

Cheers,
James.
James
Wellington - NZ

Offline Chipswitheverything

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Re: Making a 201 toolholder and learning a new threading method
« Reply #4 on: December 31, 2017, 09:07:37 AM »
Nice article and pictures on making your very useful QC holders.
  The method of screwcutting keeping the topslide parallel could, I think, be facilitated a lot by using the type of quick retraction screwcutting tool holder that George Thomas designed and wrote up as a project in Model Engineer.  The tool could be flicked back away from the work to reposition for the successive cuts without having to remember and reset the cross slide for the previous position plus increment, you could just keep adding the increment when the tool tip was flicked back to the original setting.   Having said that, I haven't made one!, but with the half included angle method one just sets the c'slide back to zero after each move...   Dave

Offline Joco

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Re: Making a 201 toolholder and learning a new threading method
« Reply #5 on: December 31, 2017, 06:29:59 PM »
Dave - agree that the retracting cross slide or toolholder would be good additions to facilitate this or the angled top slide method.

Iíve been utilising my new DRO to assist in repeatability. Since I had already worked out my cutting sequence on paper to get to a target 0.54mm thread depth it was pretty easy:
Cut 1: cross 0.2mm
Cut 2: cross 0.3, top 0.05
Cut 3: cross 0.4, top 0.1
Cut 4: cross 0.5, top 0.15
Final: cross 0.54, top 0.17

I could probably be way more aggressive on cut 1 by starting at 0.3 or maybe even 0.4 and so speeding the whole process up.  But Iím still learning how hard I can push things on this lathe and with the cutter Iím using.

Cheers,
J.
James
Wellington - NZ

Offline Steamer5

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Re: Making a 201 toolholder and learning a new threading method
« Reply #6 on: January 01, 2018, 01:14:07 AM »
Hi James,
 Nice tool blocks! How do you find scalloped nuts to use? I guess in this use itís set & forget so not to bad. I tried the same idea on my lathe backstop but they are a bit hard on the hand.

On the tool block, you could ďpay ya bucks & see the water jet manĒ like I did! Fits very nicely with no touch up!

Happy New Year!

Cheers Kerrin
Get excited and make something!

Offline Joco

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Re: Making a 201 toolholder and learning a new threading method
« Reply #7 on: January 01, 2018, 02:03:02 AM »
Kerrin - happy new year and welcome to 2018.

For small amounts of use the scalloped nuts are ok. For something more high use I think knurled would be better. In this case once its set its pretty much done and left alone.

Cheers,
J.
James
Wellington - NZ

Offline 10KPete

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Re: Making a 201 toolholder and learning a new threading method
« Reply #8 on: January 01, 2018, 04:21:11 AM »
Hi James,
 Nice tool blocks! How do you find scalloped nuts to use? I guess in this use itís set & forget so not to bad. I tried the same idea on my lathe backstop but they are a bit hard on the hand.

On the tool block, you could ďpay ya bucks & see the water jet manĒ like I did! Fits very nicely with no touch up!

Happy New Year!

Cheers Kerrin

Kerrin, you say  it fitted with  no adjusting? Wow, what sort of tolerance did they hit?

Pete
Craftsman, Tinkerer, Curious Person.
Retired, finally!
SB 10K lathe, Benchmaster mill. And stuff.

Offline Steamer5

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Re: Making a 201 toolholder and learning a new threading method
« Reply #9 on: January 01, 2018, 06:54:27 AM »
Hi Pete,
 Ummm errrrr will I didnít measure the fit, just stuck it onto the main block & it locked up great!
My eldest son had done the original drawing, which we had measured up from ONE block, of memory serves. I had the shape cut out of 6mm & it was close but didnít fit. So this time I measured up all my holders averaged up the numbers drew it up. The guy cut one & got me to try it before he did the other 2.
Iíll get my act together & post up what I built. As to measuring the fit I guess I could try using feeler gauges....would that work?
James sorry to side track your thread!

Cheers Kerrin
Get excited and make something!

Offline petertha

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Re: Making a 201 toolholder and learning a new threading method
« Reply #10 on: January 02, 2018, 08:07:40 PM »
Nice tool holder. On a side note, how do you like that style of threading insert / tooling? I'm considering the same.

Offline Joco

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Re: Making a 201 toolholder and learning a new threading method
« Reply #11 on: January 12, 2018, 02:21:36 AM »
Nice tool holder. On a side note, how do you like that style of threading insert / tooling? I'm considering the same.

I'm rather liking the threading inserts.   I've used them when threading right-to-left and when running the lathe in reverse and threading left-to-right.  They work well even when only going 60rpm.

The only down side is that if you want to thread really close to a shoulder they can't get that close. I think you will need to grind a custom HSS bit with an offset point.   But not had to do anything like that yet.  I've managed to thread to a shoulder with a 2mm "gutter" between shoulder and thread using these inserts.

Cheers,
J.
James
Wellington - NZ

Offline 10KPete

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Re: Making a 201 toolholder and learning a new threading method
« Reply #12 on: January 12, 2018, 02:45:39 AM »
Hi Pete,
 Ummm errrrr will I didnít measure the fit, just stuck it onto the main block & it locked up great!
My eldest son had done the original drawing, which we had measured up from ONE block, of memory serves. I had the shape cut out of 6mm & it was close but didnít fit. So this time I measured up all my holders averaged up the numbers drew it up. The guy cut one & got me to try it before he did the other 2.
Iíll get my act together & post up what I built. As to measuring the fit I guess I could try using feeler gauges....would that work?
James sorry to side track your thread!

Cheers Kerrin

Thanks for the info, Kerrin.

Pete
Craftsman, Tinkerer, Curious Person.
Retired, finally!
SB 10K lathe, Benchmaster mill. And stuff.