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Member postings for Roderick Jenkins

Here is a list of all the postings Roderick Jenkins has made in our forums. Click on a thread name to jump to the thread.

Thread: Fusion 360 CAM Milling
11/05/2022 19:21:53

Wow, All that in less than an hour!

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



11/05/2022 16:10:30

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:

denford 3d test.jpg

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!

360 options.jpg

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.



Thread: New Badges for an MG A
11/05/2022 15:16:01

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



Thread: Spindle depth stop
06/05/2022 12:21:56

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

If you do want to do it like that:

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

myford spindle end 1.jpg

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

myford spindle end 2.jpg

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)

lathe depth stop.jpg



Thread: Weird Collet Thread
26/04/2022 19:54:10

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



26/04/2022 17:13:31
Posted by JasonB on 26/04/2022 14:37:17:

Michael, no real need to look as 25mm divided by 30 is 0.8333, it's just one of those odd metric/imperial combinations which answers where the pitch came from.

Bit like 20tpi on shanks of metric milling cutters

Edited By JasonB on 26/04/2022 14:38:16

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.

26/04/2022 12:52:30

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?


Thread: Flexispeed main bearing replacement
20/04/2022 13:17:45

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.

old spindle.jpg

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.


19/04/2022 17:01:39

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.



Thread: Phosphoric Acid experiment
18/04/2022 15:20:18

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.


Thread: Making a Drawbar
15/04/2022 16:49:56


I have sent you a PM.


Thread: What Did you do Today 2022
14/04/2022 13:09:47

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


Thread: Wanted "Minnie" book
12/04/2022 14:27:25

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


Thread: Murad Cadet Restoration Project
12/04/2022 10:49:55

Nice job. A useful solid looking lathe yes


Thread: Sanderson Beam
11/04/2022 19:19:09

Here's the relevant bit of the current drawing:



Thread: Myford taper turning attachment part
11/04/2022 18:20:58

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

tt arm.jpg



11/04/2022 17:05:32

Another previous thread here: **LINK**


Thread: Making a Drawbar
07/04/2022 21:13:35


Thread: UK plans eight new nuclear reactors to boost production
07/04/2022 20:07:53
Posted by duncan webster on 07/04/2022 19:35:41:

Rolls Royce reckon they could have one running by 2029 if they start now, but it will take until then to get all the public enquiries and court cases over with. We pay politicians to take these sort of decisions, but they continually dodge responsibility

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


Thread: Making a Drawbar
07/04/2022 19:59:22

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.


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

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