Member postings for Roderick Jenkins

Wow, All that in less than an hour!

Thank you. I'll give it a whirl and see what happens

Cheers,

Rod

I have decided that it's about time I investigated the 3D milling capabilities of my Denford/Sherline Mach3 converted mill.

To this end I have drawn a simple test piece to be cut from 1" square aluminium alloy:

A 3D adaptive clearance should rough it out OK but I am at a bit of a loss as to what to choose for finishing. There are a lot of alternatives even in the free to use version!

I'll be using a 3mm ball end 2 flute cutter and the spindle can run up to 10,000 rpm.

Any suggestions including feeds, speeds and step-overs for initial attempts would be gratefully received.

Cheers,

Rod

Very nice. How did you do the texturing on the bar?

Cheers,

Rod

All good advice, even if most of is "Ooh you don't want to do it like that"

If you do want to do it like that:

The end of the S7 spindle is machined on the external surface:

Make a close fitting collar that can be fastened to the end of the spindle with a couple of grub screws with brass pads to protect the spindle end

Thread this collar for a suitable length of studding locked at the required depth with a nut

(the collar shown in the photo is actually for my depth stop which only works as a chuck depth stop and is adjusted from this end so the hole is plain. The depth is adjusted by the 40tpi thread in the 2MT blank. The collar stops it from flopping about - see below)

HTH,

Rod

Thanks guys, especially DC31K. I am much more comfortable now I can see some logic in the system. Everyday is a school day

Cheers,

Rod

But, as I understand it are 20 tpi, not some nearly but not quite metric equivalent.

Anyway, the responses suggest that Schaublin took the American Webster Whitcomb imperial pitches and converted them to the nearest convenient setting on a metric lathe. Seems reasonable but I wonder why they didn't choose 1mm like many of the other collet manufacturers.

The draw bar thread on a Schaublin W10 Collet is 0.833mm buttress. Where has this pitch come from? W20 collets have a 1.693mm pitch which is 15tpi. One might suppose that W10 collets have a 30tpi thread but that is 0.847mm not 0.833mm (which is 30.5 tpi).

Any thoughts?

Rod

It's a complex problem. Nominally "soft" bearing materials like white metal (Babbitt) work because there are harder crystals in a soft matrix. I imagine that Aluminium ALLOYS can offer a similar microstructure since the more advanced alloys are age hardened which means that by either time and/or heat treatment harder components are allowed to precipitate out into the aluminium matrix.

Here's the spindle of a Flexispeed lathe that I refurbished.

Galling and wear can be seen at the headstock end. With the aid of some blue and 1/2" silver steel I could not find any indication of wear in the headstock. One of the problems with buying these small lathes second hand is that they have often been used without a countershaft (as mine was). This means that they have spent much of their life running at considerably more than the recommended maximum speed of 1000rpm.

Rod

In all the Flexispeed and Simat lathes I have seen there is no separate bearing. The spindle is un-hardened and bears directly in the cast iron of the head stock. It is usual for the spindle to have much more wear than the headstock.

Cheers,

Rod

This old plane iron had the phosphoric acid treatment a considerable number of years ago;

What I find interesting is that you can clearly see where the expensive cast/crucible steel cutting edge has been (presumably) fire welded to the wrought bulk of the iron.

Rod

Dell,

I have sent you a PM.

Rod

Wing foiling has got pretty popular around here:

The problem is that the water can be quite shallow, especially in Christchurch Harbour. The readily available masts ( the bit that holds the foil below the board) are too long for comfort. The masts are aluminium extrusions. After bandsawing to approximate length, the cut end was tidied up and squared off in the milling machine

The extrusion has M6 tapping size holes in the strengthening ribs so easily tapped with a M6 spiral flute tap held in a cordless drill

Job done

I've done a few of these now for friends

Rod

One on Ebay at present. Buy it now at £34.99 or make an offer. That seems to be the going rate.

Rod

Nice job. A useful solid looking lathe

Rod

Here's the relevant bit of the current drawing:

Rod

I'm reminded by looking at that thread that I made a sketch of the arm:

HTH,

Rod

Another previous thread here: **LINK**

Rod

RR have been building them for years to power our submarines so, technically, there shouldn't be any major issues.

Rod

Bear in mind chaps that we are talking about a hollow drawbar here with an internal thread on relatively thin walled tube. I'm not close to my Pultra at the moment so can't measure the wall thickness or comment on the hardness of the Pultra supplied drawbar.

Rod

Edit: Dell , Out of interest, what is the diameter of the Pultra draw bar?

Edited By Roderick Jenkins on 07/04/2022 20:02:40