Author Topic: Building an ER collet chuck from scratch for a Myford ML7  (Read 31667 times)

Offline arnoldb

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Building an ER collet chuck from scratch for a Myford ML7
« on: August 22, 2009, 08:16:00 PM »
Following on from my own research, questions asked (and answers received) from another post here, and some other considerations - mostly related to personal finance and the backward location I live in (*), I have decided to build my own ER type collet chuck for my Myford lathe.

This is not the easiest (nor necessarily the best) option, but will provide me with some additional machining skills, personal satisfaction, as well as stress relief, and hopefully, a usable tool as an end result.  If this "quest" adds to anybody else's knowledge, or serves as a spark of inspiration for someone, that would be an incalculable bonus.

I have not yet decided on a specific ER size, but it will either be ER25 or ER32.  I need to see what size collets local suppliers here in Windhoek can get - if they cannot or are not prepared to get collets, or those are too expensive for my budget, I'll make those as well.

So, how can I start on a collet chuck without knowing the sizes ? - well, I will need to machine most of the chuck on my lathe's spindle, so the first step in making the chuck, irrespective of size, would be to machine it's spindle mount in raw stock. Not being an entirely competent machinist yet, I decided the easiest way to accomplish this would be to make a clone of the myford's spindle nose first, and as accurately as I can, to use to test the collet chuck-in-making's mounting.  If you want to propose Ebay, Chronos et al at this point in time for a solution, please refer to (*) above... No offense intended  :(  As a bonus, I'll have a spindle nose adapter for use in other project.

Right, rules of engagement laid: Make a Myford spindle nose adapter.
I used a piece of "suitable" HRS I had available to do this; the metal used is not critical (I think ? :smart: ). This was chucked up (I used my 3 jaw chuck's outside jaws, as one of the inside jaws has a broken inner tooth, and grip would be border-line - or break more teeth):


This lot was _very_ gently faced off without tailstock support to just beyond the bandsaw marks with a very sharp toolbit, then center drilled so I could add tailstock support.
Then I took a "deep" (for me) 30 thou" cross cut with the tool bit set at an angle that would "undercut" the scale and rust - saves effort on sharpening the cutting bit  :D - and immediately cleaned all the swarf from the lathe-ways and slides - the scale works like grinding compound on the lathe's sliding surfaces.

After this some plain turning to get to dimensions - this metal is horrible to get a nice finish on!:


I left the register part 1/2 thou oversize - to work down as needed, as this is the most critical. Then I needed a 55 degree thread cutting bit, which I didn't have, so I just free-hand ground one for my "semi-quick-change toolholder" from 4mm round HSS, checking with a fishtail to get the correct angles:


After grinding, I just moved the bit further back into the holder to minimise overhang.

Then set up the change-wheels on the banjo for 12 tpi for the thread cutting part. Apologies to everyone who knows this, but maybe someone can appreciate the following:  Use a strip of paper while pushing together, and turning, the gears manually to set gear spacing - feed the paper in while turning the gears, and when it passed through, just tighten up the banjo (or gear stud mounting) - And DON'T forget to add a drop of oil to the gear studs/runners and gear teeth!:


Humble pie  :whip: :whip: - I forgot to take photos of the next steps....   :( - well, I simply got busy...
I first turned a groove for thread run-out next to the index ring, and spent many back-and-forths to thread the nose.  Somewhere along the line, I think some dirt got stuck in the Myford's clutch (How do you people do single-point threading without a clutch  :scratch:  :scratch:), causing some creep even when the clutch was disengaged (or should that be engaged??)  Luckily, this was an imperial cut, so, for the first time since I've had my lathe I could use the thread dial indicator and disengage and engage the leadscrew as needed - MUCH easier than doing Metric threads on the old girl  :headbang:

After turning and cleaning up the threads, I tried screwing on my 4 jaw ( :doh: not THAT kind!!), as well as dog-plate carrier. The last went on smoothly, but the 4-jaw refused, so I used engineer's blue (a.k.a. Prussian blue) to check for the problem.  I know my 4-jaw is the tightest on the lathe's own spindle, so if that can fit, everything would be sort of OK.  The blue showed the register was still too big, as I intended, so I used some oil-coated 320 grid sandpaper to get rid of the oversize. - the 4-jaw ended up screwing on with <approximately><exactly>  :lol: the same "feel" as it does on the lathe spindle - that should be good enough for now  :coffee: :


The results of this afternoon's work:

and


 :beer:, Arnold

Offline sbwhart

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Re: Building an ER collet chuck from scratch for a Myford ML7
« Reply #1 on: August 23, 2009, 02:37:18 AM »
Nicely done and shown Arnold :beer:

This link http://www.arceurotrade.co.uk/Catalogue/Collets/ER-Collets-Collet-Chucks leads to a good drawing of ER collets that should halp with the next bit of you project, hope it helps.

Have fun

Stew
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Location:- Crewe Cheshire

Offline arnoldb

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Re: Building an ER collet chuck from scratch for a Myford ML7
« Reply #2 on: August 29, 2009, 04:50:41 PM »
Thanks Stew  :beer:

At last, some more  :dremel:.

I found a supplier in South Africa that is willing to ship me tools for a very reasonable fee to Windhoek.  Stretched my budget, and ordered a set of ER25 collets from them, as well as a closer nut with integral bearing.

Visited the local engineering firm where I can buy odds 'n ends on Monday, and got a nice bit of cast-iron off-cut from the storeman. Showed off the "Fancy" I built to them, and with the storeman and the sales staff (as well as some of their engineers) surprisingly impressed, got a whopping discount  :ddb:.
What I ended up with was this lump of 200mm long 55mm diameter cast iron:


As one end of that had been machined in a lathe before, I marked and center drilled the other end, chucked it up and took off the skin part-way with a deep undercut, as well as faced the end to close to the tailstock support:


:smart: overall chuck length would be 60 mm - to allow for the spindle end, length of ER collet needed and about 5mm extra for good luck. Then onto the bandsaw to cut a piece at just over length:


Then mounted the four-jaw chuck, and centered the piece in it as closely as I could. (Twice...   :doh: The first time I forgot to check that I put the faced side into the chuck. Not being any good at gambling, of course I lost the 50/50 odds and the sawed-off face was on the chuck face first time round...) Wish I had more  :med:  :lol:
I used the 4-jaw, as I could get the most grip support from the jaws; the rest of the machining would be mostly without tailstock support.  Then faced off to get the sawed face square and to correct overall length:


As the Myford has a ~16mm spindle bore, I then used progressive drill sizes to drill through up to 16 mm - this is just below the 17mm minimum size needed for the ER25 collet chuck:


Then the CI was further bored out to a depth of 30 mm for the inner diameter for the  1 1/8" x 12 tpi thread, and a home-ground bit used to make a 3mm deep undercut at the maximum depth for thread run-out.  I then ground and honed the other end of the same bit into a 55 degree threading point, and started threading.  Note that the threading bit is turned upside-down, and that I am cutting on the back of the workpiece on infeed, rather than at the front.  This just makes life easier for me  ;) :


And finished thread:


After this, I carefully bored out the register to size, and screwed in the spindle-nose replica I made earlier.  This was a big moment... will things be OK?  Mounted my best dial indicator to test run-out on the spindle replica.   :scratch: - dial indicator must be broken; it doesn't change when I turn the whole lot through a couple of turns - just vibrates slightly  :) - I think that's a good result  :headbang: . Setup to test run-out:


And where I stopped this afternoon:


Tested some more by screwing onto my dividing head - slightly too tight.  A check with engineer's blue shows the register is OK, so the threads are the culprit.  I'll just make a tap to clean out the last bit of tightness later on  :med:.

Now I have to wait for delivery of the collets and closer nut before I can continue; it would be best if I have those for the next steps.

 :beer: Arnold
 :nrocks: :nrocks: :nrocks:

Offline spuddevans

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Re: Building an ER collet chuck from scratch for a Myford ML7
« Reply #3 on: August 29, 2009, 04:57:38 PM »
That's looking mighty good there Arnold :thumbup: :thumbup:

I've been considering whether or not to build a ER32 chuck for my lathe. At the moment I have been using the MT3 chuck from my mill, but I'd rather have a dedicated on for the lathe, especially as it would allow for longer stock to be held through the headstock.

So I'm keenly interested in seeing your build's progress  :dremel:


Tim
Measure with a micrometer, mark with chalk, cut with an axe  -  MI0TME

Offline Darren

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Re: Building an ER collet chuck from scratch for a Myford ML7
« Reply #4 on: August 29, 2009, 05:09:58 PM »
Very inspiring Arnold, that is coming along nicely... :thumbup:

Good score on the CI..... :clap:
You will find it a distinct help… if you know and look as if you know what you are doing. (IRS training manual)

bogstandard

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Re: Building an ER collet chuck from scratch for a Myford ML7
« Reply #5 on: August 29, 2009, 05:39:21 PM »
Very nice work indeed Arnold.

It sure pays dragging around a few bits you have made to places, it shows that you are a genuine deserving cause rather than a freeloader, and I have found a few places will bend over backwards to help you out.


For those in the UK who don't have the necessary to do this sort of thing, go down the page on here a bit, and you will find a couple of different sized ones.

http://rdgtools.co.uk/acatalog/MYFORD_LATHE_USERS_NEW1.html

It might also give you a few ideas on other projects to do or maybe a cheap source of those little bits you need.

Methinks that I will invest in one for my RT setup. Not that I can't do it, I am just too bone idle at the moment, and besides, my projects and 'thank you jobs' pile is growing daily.


Bogs


« Last Edit: August 29, 2009, 05:46:24 PM by bogstandard »

Offline Darren

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Re: Building an ER collet chuck from scratch for a Myford ML7
« Reply #6 on: August 29, 2009, 05:51:30 PM »
Arnold, if you ever need anything sending over that you can't get hold of you only have to shout up.... :thumbup:

Not trying to distract you, you're doing a grand job.... :clap:
You will find it a distinct help… if you know and look as if you know what you are doing. (IRS training manual)

Offline Gerhard Olivier

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Re: Building an ER collet chuck from scratch for a Myford ML7
« Reply #7 on: August 30, 2009, 03:57:34 AM »
This one is getting on just grand

Keep up the good work :bow:

Gerhard
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Offline arnoldb

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Re: Building an ER collet chuck from scratch for a Myford ML7
« Reply #8 on: August 31, 2009, 07:26:20 AM »
Thanks everyone  :beer:

For now I have to wait for the collets & nut to arrive - could be a week or two.  In the meantime I have started some other tooling; will post that up separately when I have a chance.

 :beer: Arnold

Offline John Stevenson

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Re: Building an ER collet chuck from scratch for a Myford ML7
« Reply #9 on: August 31, 2009, 07:36:27 AM »
Arnold, this is the correct way of doing this as the chuck is dependant to the lathe it was machined on.
Some of the bought ones, and Chronos and RDG have had problems in the past is that once fitted to the host lathe the runout has not been acceptable.

It can vary batch to batch.

John S
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Offline NickG

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Re: Building an ER collet chuck from scratch for a Myford ML7
« Reply #10 on: August 31, 2009, 08:51:59 AM »
Nice work there Arnold. I have an ER25 collet chuck and collets for my mill, which I am going to make a drawbar for so I can use it in the lathe for small stuff. Should be a good accessory.
Location: County Durham (North East England)

Offline DeereGuy

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Re: Building an ER collet chuck from scratch for a Myford ML7
« Reply #11 on: September 03, 2009, 06:18:51 PM »
Nice work Arnold, I have a ton of respect for one that takes on a project like this.  Lots of things I have made can be bought also and some that didn't seem available.  I always learned a lot during the process and got great satisfaction from knowing I was able to make it....

Looking forward to seeing more.

Offline arnoldb

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Re: Building an ER collet chuck from scratch for a Myford ML7
« Reply #12 on: September 12, 2009, 02:23:09 PM »
Well, had a most productive day today producing scrap.

I received the collets and closer earlier this week  :) :


The collets looks OK - I'm slightly disappointed with the closer; it's pretty rough, and full of very sharp edges, so I'll disassemble it and get rid of the sharp edges and see if there is any dirt/swarf in the bearing  :dremel:.

On to today's work.  I screwed the chuck body onto the lathe spindle, and turned the nose down to start threading for the 32mm x 1.5mm closer thread.
I took the next photo just before I used a parting tool to make a groove for thread run-out:


Then started threading - was coming close to final size and then disaster - cut half of the formed thread away  :bang: :bang:


I think the topslide moved - don't know if I accidentally brushed against the dial or what. I was turning the thread using cross-slide feed only - still need to make some clamps and additional markings to use be able to use the offset topslide method, as mine can't rotate enough... :dremel:

So that's one chuck body scrapped  :( - might be useful for something else in future.
Then I did something I never do - went into the house, got a beer to cool me down, and brought it back to the workshop to think.  Must have still been fuming when I fetched the beer, as I can hear Shrek practicing new words while I'm typing this lot up  :doh: ...

On to recovery.  One thing I have learned through this (besides to make a plan to lock the topslide  :hammer: ) is that my original choice of cast iron might not be the best.  I noticed some "chipping" in the spindle thread lead-in, so this piece of CI I have might be too brittle  :scratch:. This could potentially cause long-term problems with the much finer closer nut thread.  I have an old bolt - used to have a pair of them but the other one was already turned into other tooling.  This is nice steel of unknown origin, but it does machine OK:


Shoved that on the bandsaw to get a new body, and gave the lathe a good cleaning while the saw was doing it's job:


Fortunately, I now have all the cutting bits and steps, so next one might be easier 
As I had an open beer, further machining was out of the question, so I closed up shop for the day.  Tomorrow is another day....  :coffee:

 :beer: Arnold

bogstandard

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Re: Building an ER collet chuck from scratch for a Myford ML7
« Reply #13 on: September 12, 2009, 02:38:52 PM »
Arnold,

With regards to your closer nut with the bearing in it.

I personally wouldn't do anything with it, use it as is. It requires those sharp edges for locating the collet and after a few uses, you will find they will mellow down by themselves.

You will also find that the smaller sized collets will be fairly difficult to fit sometimes. That has nothing to do with the collet nut. It is due to the way the collets have to be forced to fit into the nut, and because the smaller sized collets have more meat in them, the harder you have to push to deform them to get them to lock in.

I have been using one of the bearing nuts for a while now, and to me, it is a fantastic bit of kit.


John

Offline sbwhart

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Re: Building an ER collet chuck from scratch for a Myford ML7
« Reply #14 on: September 12, 2009, 02:42:03 PM »
Hi Arnold

I got one of those bearing closer nuts and found it tight same as you, I spoke to John about it and followed his advice, sure enough its eased off.

Stew
A little bit of clearance never got in the road
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Location:- Crewe Cheshire

Offline arnoldb

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Re: Building an ER collet chuck from scratch for a Myford ML7
« Reply #15 on: September 12, 2009, 04:53:06 PM »
John, Stew - Thank you - much appreciated feedback!

At least a little less elbow grease on that then :D

Kind regards, Arnold

Offline arnoldb

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Re: Building an ER collet chuck from scratch for a Myford ML7
« Reply #16 on: September 13, 2009, 03:10:59 PM »
Well, new start today...
Cleaned up the new chuck body:


Then switched to the 4-jaw and drilled consecutive through-holes to 16mm, and tried my hand at an action shot while drilling on fast back-gear to 19mm (my biggest drill) to spindle-depth:


And bored the register to size using a carbide tipped bit that I honed on a bit of emery:


After this I bored out for thread run-out in the back; slowest back-gear speed & PLENTY of lube with frequent stops to clean out the swarf ribbon.  Thought it might be more difficult, but came out well.  Then I set up the change wheels for the internal thread, and set up for the single-pointing.  Decided to stop there, and do the thread tomorrow when I'm fresh.

Cheers, Arnold

 :nrocks: :nrocks:

Offline Gerhard Olivier

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Re: Building an ER collet chuck from scratch for a Myford ML7
« Reply #17 on: September 14, 2009, 10:24:53 AM »
Nearly back on track again Arnold.  I used my collet chuck again yesterday and I think you are going to get a lot of use out of the ER collets- one of the big points is that it doesnt take up as much space as a 3-jaw chuck.

"Fresh" for the single pointing sounds like a good idea.
BTW that looks a nice piece of metal ?big bolt

Gerhard
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Offline sbwhart

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Re: Building an ER collet chuck from scratch for a Myford ML7
« Reply #18 on: September 14, 2009, 01:35:53 PM »
Going well Arnold  :thumbup: it will be a real useful bit of kit when complete.

Cheers :beer:

Stew
A little bit of clearance never got in the road
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Location:- Crewe Cheshire

Offline arnoldb

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Re: Building an ER collet chuck from scratch for a Myford ML7
« Reply #19 on: September 14, 2009, 03:28:21 PM »
Thanks Gerhard, Stew  :)

Gerhard yes - a bolt... Slightly over sized for my modeling needs  :lol: - nice steel as wel, but a regular bugger to get a decent finish on.
Stew, I've been literally dreaming of getting a collet chuck - seeing them used so often just pushed me, plus it seems (from another forum) this build has started a bit of  :proj:   Didn't know I was opening a can of worms here without going fishing  :lol:

Well, a good result for today  :)  :ddb: :ddb:

This afternoon I started by turning the spindle thread in the chuck body.  A close-up down the register and thread - the pool of cutting fluid in the back is collected in the thread run-out:


Once I was happy the thread was well-done, I unscrewed the 4 jaw with the chuck body still in it and tried to screw the whole assembly onto the spindle from the collet chuck body.  The register was a touch too tight, so I turned it around again, and used some emery & oil to open up the register a bit more.  With the next test it fit very acceptably.

Removed the collet chuck body from the 4-jaw, and screwed it straight to the spindle.  Then turned down the nose end to size for the collet closer nut:


Once again the undercut using a parting tool - slowest back gear speed, as this steel is fairly tough:


Threading nearly done:


I tested the final thread size by trying to screw on the closer nut after cleaning the threads thoroughly on each attempt.  Once it screwed on full way, but slightly stiffly, I used a fine triangular needle file just to give the threads a final cleaning - after this the closer nut spun on easily, but not loosely.

Now came time for the internal taper for the collet.  I first tried the following to set the topslide to taper:


Something "felt" wrong at this point  :scratch:, so I tested a couple of different collets and got readings all over the show :hammer:    :smart:  They are all already slit and spring loaded, so there would be differences.  I settled on trusting mr. Myford  :D, and just set the top slide to 8 degrees, making sure the boring tool was set dead on center.  I know there are other ways to set an accurate angle on the top slide - but was not about to go down that route  :coffee:.  A blue test while the hole was still slightly undersized would suffice, and that's what I did, using the 10mm collet and a known-good piece of 10mm silver steel, long enough to be clamped on it's entire length.  First off, blued the collet and inserted in closer, then inserted test bar:


Then screwed the collet up tight into the chuck,carefully keeping the collet from touching the chuck initially and keeping it from rotating as I did this.  Reversed out the collet, once again preventing rotation and trying not to let it "drag" in the chuck - got the following blue marks in the chuck proving that the entire length of the collet was clamped adequately and evenly:


After this I turned the taper to just under full-size and carefully smoothed it off using some emery superglued to a wooden dowel & oil.  Then I played around with removing the chuck, installing it, chucking up different workpieces repeatedly in different rotations and a whole combination of the previous.  Biggest run-out I measured was less than 0.005 mm (less than half a division on my 0.01mm guage) - that's about 0.2 thou - I think that's acceptable  :headbang:.

Some cosmetic work externally (well, it's not a beauty  :lol:) and here is where I left off for tonight:


Tomorrow I'll cross-drill a couple of holes to take a tommy bar in the chuck body, as it is too smooth.  At a later stage, I'll knurl a ring grip on the body as well; first need to get some knurling wheels and build a tool  :dremel:  :proj:

So, that's my version of a collet chuck; pretty it's not  :lol: , but, like Stew said, I really think I'll enjoy this addition to my workshop in upcoming projects.

 :beer: , Arnold


bogstandard

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Re: Building an ER collet chuck from scratch for a Myford ML7
« Reply #20 on: September 14, 2009, 03:36:27 PM »
Very nicely done Arnold.

That post will surely show me the way when I get around to making mine.

Bogs

Offline sbwhart

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Re: Building an ER collet chuck from scratch for a Myford ML7
« Reply #21 on: September 14, 2009, 03:53:05 PM »
First class job Arnold

 :clap: :clap: :clap: :clap: :clap:

Well written up and shown

Cheers

Stew
A little bit of clearance never got in the road
 :wave:

Location:- Crewe Cheshire

Offline arnoldb

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Re: Building an ER collet chuck from scratch for a Myford ML7
« Reply #22 on: September 14, 2009, 04:12:13 PM »
Bogs, Stew - thank you very much.

Bogs, I'm pretty darn sure you'll do a much better job than I did; I'm looking forward to seeing that and a lot of  :doh: moments for where I got it wrong!

 :beer:

Offline NickG

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Re: Building an ER collet chuck from scratch for a Myford ML7
« Reply #23 on: September 14, 2009, 05:09:51 PM »
Arnold, well done. Looks a great tool. When I used mine that I bought for my milling machine in the late, it wasn't spot on, but you know yours is, as it was machined on the lathe. It proved invaluable .. I couldn't have done a couple of the jobs without it. Being a small diameter is handy too meaning you can get right up to the chuck with most tools.

Nick
Location: County Durham (North East England)

bogstandard

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Re: Building an ER collet chuck from scratch for a Myford ML7
« Reply #24 on: September 15, 2009, 02:50:52 AM »
Arnold,

Don't go putting yourself down. I am no better than you at making things.

If it does the job it is intended to do, then you are onto a winner.


Bogs

Offline arnoldb

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Re: Building an ER collet chuck from scratch for a Myford ML7
« Reply #25 on: September 15, 2009, 04:17:21 PM »
Nick, thanks - I'm looking forward to many fun projects with this; and part of the reason I built it is to be able to get in close with the cutting bits :)

Bogs, thank you.  You do have a lot more experience though, so there is always something interesting to learn from you.  I'd like to think that I'm now learning things that I can also pass on to young novices 30 years from now.

I didn't do much in the shop today, but managed to squeeze in time to drill the chuck for the tommy bar, and also made up a matching tommy bar and c-spanner from some 6mm silver steel.  For the c-spanner, I turned the tip of the length of silver steel down to 4mm. After this, I bent the curve in around a piece of 30mm rod - when I released the tension after bending, it sprung back to a nice fitting curve for the collet nose. Bending the silver steel was pretty tough going, and it got pretty warm from internal friction!
Then I picked up a scrap piece of flat iron under the bandsaw and drilled a 4mm hole in it at a slight angle, and silver soldered it to the bent drill-rod to make a nice hook.  Used the bench grinder to grind the lot to a reasonable shape, and finished off with a file and then sandpaper.

I also turned 2 pieces of 10mm aluminium rod into a matching pair of handles, and loctited those to the c-spanner and tommy bar:


Now all that is left, is to make a nice wooden storage case for the chuck, accessories and collets - this I'll do in the next week or two when I plan to do some work on my kitchen cabinets - I can do OK woodwork, but don't like the mess, so I'll lump all the woodwork together in a single go.

Regards, Arnold

Offline Gerhard Olivier

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Re: Building an ER collet chuck from scratch for a Myford ML7
« Reply #26 on: September 15, 2009, 04:27:39 PM »
That looks good Arnold

You are going to get a lot of good use out of that.

Looking forward to the knurling blog -I dont like the way my knurl workes so it needs a redesign - will wait and see what you come up with first.

Nice job

Gerhard
Guernsey
Channel Islands