Machining flats on bar stock

[DollyDiggerParticipant @dollydigger]

Hi

Lets take a 15mm bar 100mm long, put in the lathe and cut 20mm in to leave 12mm stubs ea end.

Put the bar in the vice on the mill and machine a flat across the 12 mm end 4mm from ctr.

I want to machine a flat at 90 degrees to the first one on the other end, i would like it to be as accurate as possible, how would i go about this?
cheers
Malc

[DollyDiggerParticipant @dollydigger]

[Anonymous]

Use a collet block?

[Robert Atkinson 2Participant @robertatkinson2]

Don't put it in a vice, clmp it in a V block (or pair) machine one flat. Flip it over and clamp the loosly in V block and clamp the flat to the face of a square block (3-2-1 block?) or angle plate sitting on the bed, and tighten the V bloc clamp(s)

Robert G8RPI.

[John HaineParticipant @johnhaine32865]

How wide is your vice? If you can get each end sticking out set the first flat vertical with a square off the table.

[JasonBModerator @jasonb]

This is when two sets of collet blocks come in handy so you can cut one end with minimal overhand, then swap to the other while both blocks are on a flat surface, remove first block and machine second end in the second block

Alternative is to hold in the vice with one end over the side and mill the first flat, clamp a Vee block to the 12nn dia with a square against the vee block. Then loosen vice rotate 90 deg and use the square against the next side of the vee block to set your 90deg. I read a good book recently that shows this method

[HOWARDTParticipant @howardt]

If you can stand a radius at the end of me flat. Hold the bar in two opposed every blocks in the vice, this will give enough room if the part is short to roll mill one end and end mill the other without moving the part.

[DollyDiggerParticipant @dollydigger]

I have never heard of collet blocks, i shall go away and read up, thank you all, very helpful

malc

[Ramon WilsonParticipant @ramonwilson3]

If you have one, an option would be to use an angle plate – do the first end in the mill vise, clamp the milled end to the angle plate lightly clamped to the table, align with the vise and retighten. Tighten vise and mill second end.

It will be as accurate as the angle plate is square.

Well that's how I would do it

Regards – Ramon (Tug)

[not done it yetParticipant @notdoneityet]

Two vises will do the job easily enough. Cut the first, then mount the bar with the flat against the fixed jaw. Hold the other end with another vise and mill that end. So lots of alternatives, depending on your kit available.

[DollyDiggerParticipant @dollydigger]

I never thought there would be so many methods, i have never enjoyed learning so much before

thank you

[Ian PParticipant @ianp]

I did a similar thing on a 20mm diameter bar 1.8m long. I used a precision level (clamped to the first machined flat) as a reference. I have (temporarily) forgotten how I allowed for the milling machine not being precisely level but as its not bolted down I made sure it did not move between operations.

IanP

[mechman48Participant @mechman48]

For that size a15 mm collet in a Stephensons square collet block would be the way to go, at least that's the way i would do it, there again I do have square & hex collet blocks.

George.

[DollyDiggerParticipant @dollydigger]

I was quite impressed with what collet blocks can do, i have orderd a set and inc 15mm collets and off we go

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