Work Holding

[Speedy Builder5Participant @speedybuilder5]

Below is a photo of my latest bit for a vintage car – just a simple starting handle dog. I post this for others to see that when milling, it is advisable to place some sort of support under the piece being machined to reduce vibration etc.
BobH

The old dog had split due to the shaft being screwed into the hardened dog and eventually splitting it – there must have been a lot of brute force at some time. Perhaps even stress cracks during the hardening process.

[Speedy Builder5Participant @speedybuilder5]

Work holding on Rotary table / mill

[HopperParticipant @hopper]

Nice job. And certainly a good tip, especially on the smaller less rigid machines.

[Eric CoxParticipant @ericcox50497]

One could argue that the chuck isn't big enough as it prevents you from reducing the overhang by not having a large enough throat on the chuck.

[David Clark 13Participant @davidclark13]

One could argue that if you turned the shank down it would fit in the centre of the chuck.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Eric Cox on 07/11/2015 08:56:47:

One could argue that the chuck isn't big enough as it prevents you from reducing the overhang by not having a large enough throat on the chuck.

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So … Eric … Is one expected to have a pool of machines and accessories to best-meet every requirement? … Or does one "engineer" an effective work-around?

MichaelG.

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P.S. My thanks to SB5 for taking the latter approach, and sharing.

[David ColwillParticipant @davidcolwill19261]

Yes but then no chuck you ever own will be big enough. There is a mathematical formula that proves this, commonly referred to as sods law.

Whilst this is a simple and on the face of it obvious idea, I wish I had thought to do it a couple of weeks ago when I attempted a job with a similar overhang.

Regards.

David.

[Speedy Builder5Participant @speedybuilder5]

Eric C- then the spindle nose would have crashed into the larger chuck jaws.
David C 1 – Why waste valuable material when a simple solution exists.
And thank you M G and D Col.
BobH

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, I used a similar method in the photo below. Although this section of box is 12mm thick, it was able to deflect even under the slightest of cuts.

Regards Nick.

[AjohnwParticipant @ajohnw51620]

It doesn't matter how big a persons kit is jacks are sometimes needed. It all depends on the part. Personally for support I'd like to see a lock nut nut but if I didn't happen to have one ………………….

John

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[LambtonParticipant @lambton]

The set-up is fine for the application however I would like to see a small radius in the corners rather than a sharp one to prevent any stress caused by normal use becoming a problem.

[Speedy Builder5Participant @speedybuilder5]

Lambton – you are dead right there. Fortunately, there is now an electric start fitted and the hand crank is for flat batteries / valve timing etc, but I take your point and it is easy to forget these little details which can make a BIG difference.

[David Clark 13Participant @davidclark13]

I thought the component had the shank turned integral. Anyway it was only a bar end of steel. Steel is worth *** all nowadays anyway.

[martyn nutlandParticipant @martynnutland79495]

Hello Speedy

Congratulations on a very neat starter dog. I had to make a couple of these and at the time could only perform the operation by saw and file.

If it's not too much trouble I wonder if you could tell me how exactly you set up the tooling to cut this as I would like to learn for the future?

Thanks in advance.

Martyn

[Speedy Builder5Participant @speedybuilder5]

Martyn,
Turn bar stock to required diameter
Drill / bore to internal thread diameter (or to size if the shaft is a push fit etc).
Remove chuck from the lathe and mount onto the rotary table – make sure it won't come off whilst milling.
Mount the rotary table such that the axis of the chuck is in the horizontal plane and that it is 30Deg. (or whatever angle) from the X axis (i.e. axis Left to Right as you stand in front of the mill).
Use an end mill at the required depth (More than half the depth of the dog diameter) and gently remove material to the required depth.
Rotate the chuck 180Deg and repeat for the other side.
Remove chuck and return to the lathe.
Part off to required length.
Mount the dog in the lathe and clean up the end face.
Screwcut the thread and clean up with a plug tap afterwards.

Hope these notes help.
BobH

[martyn nutlandParticipant @martynnutland79495]

Bob

Many thanks. I can go from there.

Wasn't sure you had involved a milling machine. Now I know you did, much more obvious.

Thanks again.

Martyn

[Speedy Builder5Participant @speedybuilder5]

I am fitting a revised superheater header / steam pipe to a SPEEDY boiler and have to enlarge the thread from 1/2" to 5/8". Using a boring head in the Boxford lathe. I am just showing a very crude work holding setup for holding the boiler onto the saddle prior to using the boring head to enlarge the hole prior to tapping 5/8 x 26 tpi. The top slide has been removed and the rear of the cross slide had already been tapped 5/16 BSF for a parting off tool. As a safety precaution, I leave the motor drive belt slack and rely on a loose belt to turn the headstock – if a snarlup occurs, hopefully the motor belt will slip. ??
BobH

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