Clarke CL500M half nut conversion

[Stuart Cox 3Participant @stuartcox3]

Posted by Danni Burns on 15/05/2021 15:07:28:

Thanks Stu

Its not making perfect sense at the moment.

I can see you've gone from 4 bolts in 4-Jaw chuck bolts to 3 for connecting to headstock

What are the half threads for on the ID (is there 4 of them)? probably associated with the 4 bolts on new Chuck?

Im sure it'll all make sense when I take the 3 jaw off.

Thanks for sharing

..yes, they are the back end of the 4 bolt holes that hold the 4 jaw to the back plate

Stu

[Danni BurnsParticipant @danniburns84841]

Hi guys

I've just received my 4 jaw chuck and am about to ask around my contacts for a blank 160×20 as advised by Stuart.

Would you mind advising what is the best material for the blank/adapter?

Thanks

[Stuart Cox 3Participant @stuartcox3]

Posted by Danni Burns on 20/05/2021 22:15:52:

Hi guys

I've just received my 4 jaw chuck and am about to ask around my contacts for a blank 160×20 as advised by Stuart.

Would you mind advising what is the best material for the blank/adapter?

Thanks

I actually used steel for mine and I don't have any issues. I bought my blank from a company online called rapid metals, they have a large selection of materials at a good price. I paid about £20 for the blank inc delivery.

I think most people recommend cast iron but I didn't want the mess from the machining. I've seen some use and old dumbell weight machined to size.

Stu

[HopperParticipant @hopper]

You might as well use steel for the backplate. Many of those Chinese chucks have a steel body anyway.

Cast iron might be marginally better for a backplate because it tends to dampen vibration/resonance better than steel and resists deformation better. (Young's Modulus notwithstanding, it resists deformation under compression more than steel does.) But for the small advantage probably not worth the dirty abrasive mess when machining it.

So at the end of the day, personal choice really.

[john halfpennyParticipant @johnhalfpenny52803]

Chronos sell a suitable 160mm cast iron blank. Easier to machine, but messy.

[john halfpennyParticipant @johnhalfpenny52803]

Chronos sell a suitable 160mm cast iron blank. Easier to machine, but messy.

[Danni BurnsParticipant @danniburns84841]

Thanks all. Noted about the Cast Iron v Steel

i actually have a load of weight not being used, so may look at that. I'd have have thought that cast would be crap quality though,

Normally I would have no hesitation, but with this mini machine I have yet to build any confidence with. Possibly I can get machined outside.

Stu/John any chance you could post a photo of the insides of your adapter or drawing?

Cheers

[Stuart Cox 3Participant @stuartcox3]

Posted by Danni Burns on 21/05/2021 11:25:04:

Thanks all. Noted about the Cast Iron v Steel

i actually have a load of weight not being used, so may look at that. I'd have have thought that cast would be crap quality though,

Normally I would have no hesitation, but with this mini machine I have yet to build any confidence with. Possibly I can get machined outside.

Stu/John any chance you could post a photo of the insides of your adapter or drawing?

Cheers

I didn't make a drawing for my adapter Danni, there's not much to it to be honest, just measure the recess in the back of the 4 jaw and the chuck mount on the lathe. Once you've cut those you can put in the adapter in place and mark the holes for the fixing bolts. I made mine on the Clarke and it coped well!

Stu

[Danni BurnsParticipant @danniburns84841]

Thanks Stu

Its beginning to make sense now. Are the 3 Threads in your photo studs?

I havent measured anything yet, but I this is my current understanding of the plate design.

Do let me know if you see anything glaringly incorrect.

Thanks

[martin perman 1Participant @martinperman1]

Danni,

My three and four jaw chucks are both machine mart and they have three bolts to hold them on the spindle plate, I found that the three bolts have the same pitch but not the spacing, one bolt is ever so slightly closer to one of the other bolts and I've centre punch the plate and chucks to make sure they fit correctly.

Martin P

[Stuart Cox 3Participant @stuartcox3]

Looks fine to me! The only thing I can't see clearly on the cross section is the recesses for the lathe mount and chuck mount but I see they are marked on the front view. Yes I put studs in the back as its easier when you sit the 4 jaw in place then spin some nuts on than trying line up the bolts while supporting the weight of the chuck. It's a useful thing to do on the 3 jaw too if you haven't already.

Stu

[Danni BurnsParticipant @danniburns84841]

Hi Stu

That's the 0.099 and the 0.008mm on the side view

You cant see the top line as its covered by the top stud. It got a bit congested to add any further detail.

I feel now if I exchange all of the dimensions for actuals I will have it sorted.

BTW I have never taken the 3-Jaw chuck off. I will obviously to get the dimensions.

I'm guessing those studs should be High tensile steel as well? Probably buy some bolts and cut down.

thanks

[Danni BurnsParticipant @danniburns84841]

Hi Martin

Thanks for that – My 4-Jaw is exactly the same as Stu's (San ou K72-160 160mm (6&quot 4 Jaw chuck), hence the 4 bolts (through the chuck into the plate) and the 3-studs (which should be same as yours),

Would you mind sharing a pic of the back of your 4-jaw chuck? Maybe tell me what that diameter is (for a sanity-check when I measure).

cheers

[martin perman 1Participant @martinperman1]

I will do that tomorrow if ok, bad weather and household chores means today is already laid out for me

Martin P

[john halfpennyParticipant @johnhalfpenny52803]

Danni, you will need about 20mm starting width from which to machine a 4mm recess and a 4mm boss, whilst leaving enough meat in the middle for the chuck attachment screws ( because the recess coincides with the attachment screw threaded holes). Full chuck dimensions are on some ebay listings.

[Danni BurnsParticipant @danniburns84841]

Thanks Martin – pubs are open as well

John – Hi and Thanks again. So Recess on one side (where i have 8mm) and Boss on other side where I have flush. Is that correct?

If all holes are coinciding with recess – best to drill those first.

I have just looked on vevor where I bought and not enough details – to make a drawing anyway. It is definitely Cast Iron though. Will look on ebay and double check on actual before starting.

[Danni BurnsParticipant @danniburns84841]

Hi Stu

Regarding the struggle while swapping chucks. You recommend replacing these bolts with studs and nuts?

[Howard LewisParticipant @howardlewis46836]

Mini lathes use studs and nuts, for reasons of space.

But studs remove the problem of the eventual wear of the threads in the chuck. At least a worn or damaged stud can be replaced pretty easily.

But you can get very frustrated searching for dropped nuts!

Danny M2Z made a very useful, simple, gadget for holding the nuts for fitting or removal.

It starts life as a bit of flat metal Two cuts, one bend and a bit of filing and dropped nuts are very rarely a problem.

There is no reason why it could not be scaled up, to suit fixings larger than M6.

Howard

[Stuart Cox 3Participant @stuartcox3]

Posted by Danni Burns on 21/05/2021 16:18:42:

Hi Stu

Regarding the struggle while swapping chucks. You recommend replacing these bolts with studs and nuts?

Yes that's right. It's easier to slide the studs through the holes which will then help support the weight of the chuck while you fit the nuts on to the studs.

Ref your drawing, as John mentioned it is important you have a boss on the front of the back plate you're going to make so that it centralises and supports the 4 jaw chuck, just like there is on the front of the lathe chuck mounting plate. That's what I couldn't see on the cross section in the drawing.

Once you remove the 3 jaw chuck you will see the boss and the recess to take your measurements from for the rear of your new back plate. For the boss on the front of the back plate you need to measure the recess in the back of the 4 jaw chuck.

Hope that makes sense, I'm not particularly great at explaining things!

Stu

[Danni BurnsParticipant @danniburns84841]

Hi Stu

Yes. Makes sense. I think doing the drawing was worth while now.

I will measure all up and modify the drawing. I'll ask you and John to check then. Hopefully other will be able to use.

Howard

What's this M2Z thingymabob. Have you got a pic?

cheers

[Howard LewisParticipant @howardlewis46836]

Hi Danny,

There was an article, some time ago in MEW, by Danny M2Z. Think that he lives in Oz or NZ.

I made one out of a bit of steel strapping. It is that simple, even I can make one that works!

One bend is to act as a short tongue that enters the nut as it comes to the end of thread, and by holding the nut against the main part of the tool, prevents the nut from falling off.

SO simple, and SO effective!

I'll take a shot of it and send it to you.

This will be for M6 studs and nuts. It allows the nuts to be tightened or slacked with a 10 mm A/F Open End spanner, starts or completes the process, leaving the rest to be dome with fingers, without dropping the nut.

Saves a lot of frustration (and wear on the threads in the chuck ).

Just needs scaling up for larger size studs and nuts.

Howard

[martin perman 1Participant @martinperman1]

Posted by Danni Burns on 21/05/2021 15:17:33:

Hi Martin

Thanks for that – My 4-Jaw is exactly the same as Stu's (San ou K72-160 160mm (6" 4 Jaw chuck), hence the 4 bolts (through the chuck into the plate) and the 3-studs (which should be same as yours),

Would you mind sharing a pic of the back of your 4-jaw chuck? Maybe tell me what that diameter is (for a sanity-check when I measure).

cheers

Danni,

My Machine Mart 4 jaw has no makers mark and is mounted onto a steel back plate the OD of the chuck and back plate are both 149.60mm dia, the back plate is 12mm thick and the recess is 3.55 mm deep and 99.90mm dia and the PCD of the three tapped holes to mount it on the spindle is 131.6mm dia.

The hole in the centre of the back plate is 32mm.

Hope this helps,

Martin P

Edited By martin perman on 23/05/2021 14:09:44

[Danni BurnsParticipant @danniburns84841]

Thanks Martin

I will update my drawing with those details and see where Im at.

I bough the cast iron blank. Unfortunately it has a big boss in the middle that to get rid of. May be messy like Stu mentioned.

cheers

[Howard LewisParticipant @howardlewis46836]

When machining cast iron, I place a powerful magnet under a sheet of newspaper, or cloth (So that it does not get caught up) where it is likely to fall, to attract as much as possible of the swarf.

It will not catch all, but it makes the job a little less filthy!

Obviously do a really thorough clean up afterwards.

Howard

[Danni BurnsParticipant @danniburns84841]

I hadnt thought of magnets, but have a couple so will definitely try that out.

I do intent to run a vacuum, hopefully I can position the nozzle to catch the majority.

cheers

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