mandrel handle

[here againParticipant @hereagain]

Now I m doing a fair bit of threading on my lathe I want to make a mandrel handle..Very simple except how to attach the shaft to the mandrel..It s a smooth tube through to the backplate and chuck..As its a speed controller type I really dont want to take it out to alter it..How please? Jonathon

[here againParticipant @hereagain]

[Michael GilliganParticipant @michaelgilligan61133]

Usual arrangement is an expanding tube, with a draw-in tapered plug … Same concept as the old style bicycle handlebar stem.

I'm sure someone will be along soon, with a drawing or photo.

MichaelG.

[here againParticipant @hereagain]

Ah..Yes..Actually I d thought of something like that but thought the expanding bits will crack after a while..Bit like a reverse collet..What can I make it from ?

[Clive FosterParticipant @clivefoster55965]

Quick'n dirty way is a big expanding concrete anchor bolt or stud (rawlbolt) inside an alloy tube suitably slotted so it expands when the bolt or stud is done up. Alloy tube protect the spindle bore and improves grip. Alloy on steel holds better thans teel on steel. Tube should be a close sliding fit in the spindle bore with a flange on the end to set the longitudinal position. I'd make a short length just forward of the flange a touch larger making it a push rather than sliding fit. Use a reasonably long bolt or stud so at least an inch of the tube can be nominal clearance size helping to support it nicely on centre line.

I use a smaller version of the same idea on a regular basis to make ad hoc pullers gripping the internal bores of bearings and such. Expanding part works in up to 1/4" wall thickness, maybe more.

Clive

[here againParticipant @hereagain]

Got it.Thanks..Jonathon

[Jon GibbsParticipant @jongibbs59756]

Hi Jonathon,

My mandrel handle is based on the design in Ian Bradley's book on the 7 Series Myfords…

and here's a picture. It's just made out of BMS and after 2 years of regular use it's still going strong.

Mine uses M6 studding loctited into the outer knurled nut and four slots (easier to drill the relief holes). The inner nut with tommy bar hole is used to tighten up the tapered plug into the socket. Note: that the male taper is only threaded and is free to move – it doesn't rotate in use as might be expected.

After it's been tightened it does take a light tap on the slackened off outer knurled nut to free up the taper.

HTH

Jon

[not done it yetParticipant @notdoneityet]

Depends on what you wish to thread. If it needs to project down the mandrel, the options above are good. On the other hand, if none need to be mounted further back than the chuck jaws, a threaded taper sleeve at the chuck end of the mandrel will suffice, the handle being tightened to the mandrel by a locking nut on the drawbar. Nearly all lathes will take a centre for turning between centres, so it is unlikely your lathe mandrel is a parallel tube?

[HowiParticipant @howi]

You do not need anything as complicated, the shaft of the mandril just needs cutting at 45° or whatever angle you want. As you tighten the mandril the two cut faces will slide against each other and push the two halves of the shaft apart thereby jamming the shaft inside. Easy peasy

[Douglas JohnstonParticipant @douglasjohnston98463]

I may be a bit slow on the uptake this morning Howi but I don't understand your idea. Can you explain the idea further, perhaps with a diagram or photo?

Doug

[Michael GilliganParticipant @michaelgilligan61133]

Doug,

I think Howi means something like this fixing:

**LINK**

http://www.edinburghbicycle.com/products/adjustable-quill-stem?&gclid=CK_tg7-7ts4CFUQW0wodkOMETQ

MichaelG.

[HowiParticipant @howi]

Yes! That's the idea, I split mine about half way down the shaft. There are a number of diagrams out there but I just made mine up as I went along. Had it done in an afternoon, one of the most useful tools I have made, can't understand why I did not make one sooner 

 

[Jon GibbsParticipant @jongibbs59756]

I like the simplicity of the wedge design but if it slips, which my mandrel handle does often if I don't tighten it up enough, then isn't there a possibility you are going to score the inside of the mandrel?

The opening up collet design is more or less smooth on the inside gripping right around and not in one or perhaps two places.

Just a thought

Jon

[Tony Pratt 1Participant @tonypratt1]

The opening collet design will in theory give more grip.

Tony

[Roderick JenkinsParticipant @roderickjenkins93242]

Posted by Jon Gibbs on 10/08/2016 11:32:54:

I like the simplicity of the wedge design but if it slips, which my mandrel handle does often if I don't tighten it up enough, then isn't there a possibility you are going to score the inside of the mandrel?

Possibly. However, on my Myford S7 at least, the through hole is just drilled and has no particular finish so no big deal. My mandrel handle uses a cone rather than a wedge but if I were doing it again I would use an ally wedge – much simpler and just as effective.

Cheers,

Rod

[Clive FosterParticipant @clivefoster55965]

Making the expanding part from alloy alloy protects the spindle bore if its nicely finished and gives a better grip on a rough finished one as it can distort slightly into the 'umps and 'ollows.

Expanders can also be made using "rubber" components. One way is a stack of O rings with taper washers interposed to expand the O rings when things are tighened up. Another is a length of thick wall hose a nice sliding fit in the spindle bore on a slightly shorter support tube. When things are tightened up the hose crumples up slightly expanding against the spindle bore generating a tight grip on both support tube and spindle. I've used the hose trick on another application and it gives strong grip in twist. A touch flexi longitudinally hence not so good if you and to drive a component out by holding it internally. A lateh spindle stop using the expanding O-ring idea came in as part of a multi item purchase. Singinifcant evidence of wear so it was clearly used a lot by the original owner, probably on a Hardinge turret lathe, so muct have worked pretty well.

Whatever method you use to make the expander its important to provide enough length out of the back of the spindle so it can easily be gripped to pull it out. A teeny flange looks neat but means you pretty much have to pull it ou by the handle so the extracting force goes via the driving widget so pulling out also tends to expand it! Matters can get a bit, um, fraught!

Clive.

Edited By Clive Foster on 10/08/2016 12:55:47

[HowiParticipant @howi]

Never had mine slip, tightens up rock solid. Any scratch damage on the parallel portion of the spindle unlikely to cause any issues, it is the M3 ( on my lathe) taper that is important and this has not been touched.

Very quick to engage and disengage.

You may use any method/design you like, but me, I like to follow the KISS principle.

 

Edited By Howi on 10/08/2016 12:56:59

[JAParticipant @ja]

I made an adoption of Ian Bradley's design The handle arm was a length of slotted steel strip. The slot engaged in the collet shaft where the 1/2" diameter end is shown and the arm was clamped in place by a collar under the nut that draws the taper into the assembly. It was simple and I never had any problems with slippage. Also it was very easy to remove once used unlike the Myford supplied mandrel that can need encouragement if pushed fully home in the bore.

Unfortunately I gave it away when I sold my Myford Super 7. It was one of the most useful, and simple, tools I have made

JA

[NobbyParticipant @nobby]

Hi Guys
My mandrel handle is sprung loaded like a milling machine handle if you let go it pops out . for safety . as its heavy it stays in place when my Myford S7 is running
Nobby

Edited By Nobby on 10/08/2016 14:40:32

[Neil WyattModerator @neilwyatt]

My version uses a fully spilt collet about 1" long, the two collet halves are kept in place with a circular spring from a keyring.

Neil

[JasonBModerator @jasonb]

I have several Mandrel handles, all follow the same basic design, in the 30 yrs I've been using them I have not had one slip, score the spindle bore or had to think twice about removing the Handle before starting. Can't see me changing method………….

 

 

 

 

 

 

 

 

 

 

Edited By JasonB on 10/08/2016 15:13:26

[Neil WyattModerator @neilwyatt]

One thought, the collet (of any design) is best made an easy push fit, this means it has to expand very little but also ensures sufficient concentricity if you also use it to mount a changewheel at the back of the lathe.

Neil

[duncan webster 1Participant @duncanwebster1]

mandrel handles are one of those things which seem to be essential equipment for model engineers, but are never seen in industry. I just screwcut under power. Only if lathe had no backgear and so wouldn't go slowly enough would I consider a manual winding handle. If cutting up to a shoulder, turn a short groove for the tool to run out into, or something I've seen suggested but never tried, run the lathe backwards and put the tool upside down (or in a back toolpost), then the tool runs off the end of the job. For internal screwcutting I usually put the tool upside down but run the lathe forwards and cut on the far side. The turnings then fall away from the tool, and you can see the tool a bit better

[Rik ShawParticipant @rikshaw]

My WM250 lathe runs at 100 rpm at the lowest speed which is to fast for my slow reactions when screw cutting. So I made a mandrel from a Halfords tyre lever and other bits which lock into the backend of the spindle. It works very well not just for screw cutting but tapping as well. (Yes, I confess to being a bit windy re: tap breakages.) When finished using the mandrel the large knurled knob is unscrewed a turn or two and the threaded rod tapped gently with a lump of lead after which the mandrel slides out freely.

 

Unlike JasonB I HAVE forgotten on several occasions to remove the mandrel before pressing the GO button but I have a cunning plan to stay safe. Before inserting the mandrel I ALWAYS turn the power of at the wall socket. It is a golden rule and so far it has kept me safe (and momentarily surprised as well when I press GO and nothing happens.)

 

Since I made the mandrel I discovered that I have an option to reduce the lowest speed on the lathe by backing of a small pot on the speed control board. It’s one of two at the bottom left hand corner in the photo marked MAX and MIN although I have yet to make the adjustment. With the lathe running OK at the mo (touch wood) I am leaving well alone and relying on the mandrel.

 

Rik

 

 

 

Edited By Rik Shaw on 10/08/2016 17:53:13

Edited By Rik Shaw on 10/08/2016 17:57:47

[David lawrence 3Participant @davidlawrence3]

Hi Rik, I have a very similar lathe, a Warco 240 and that handle you made is just what I need, may start building it tomorrow. I have a small, warco mill, wm14 which has a similar control board, I tweeked the Min pot to the lower the speed to zero so I can turn the speed knob down to nothing rather than keep turning them mains on and off all the time, I did this a year ago when I bought the mill and it has worked fine ever since.

[Author]

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