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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: What Did You Do Today 2019
23/03/2019 09:57:25

Finished the pallet. I don't think my dodgy shoulder would have let me tap the holes by hand.

rt pallet.jpg

One half of the disc has holes on a rectangular array and the other half is radial. Not sure if this was a good idea or not. I've got a pallet on the CNC mill that's also waiting for an array of holes.


21/03/2019 21:22:24

I'm making a pallet for my rotary table. Lots of M6 tapped holes. With this in mind I bought an Archer auto reverse tapper from ebay.

archer no1 tapping head.jpg




Edited By Roderick Jenkins on 21/03/2019 21:25:18

Thread: Watchmaker's vertical slide
21/03/2019 20:25:23

My obsession with milling spindles continues: I've made one for the Lorch slide -

micro drill spindle.jpg



Thread: Tool Post Milling/Drilling Attachment
19/03/2019 16:25:11


I have successfully used a 120 Watt sewing machine motor with an Arrand spindle. 6mm drills are a bit of a struggle but it will drill 4mm with ease and drives a 6mm endmill OK providing the depth of cut is not too big. I was guided in my choice for the new system by the capacity of the ER11 collet chuck.


I couldn't really comment on use for a woodturning lathe, it depends on so much. For guidance, the top speed of the treadmill motor is 4000rpm so I would probably at least halve that speed with the pulleys for wood turning but, again, it depends...



16/03/2019 23:23:21
Posted by Robert Atkinson 2 on 16/03/2019 22:53:26:
Posted by Roderick Jenkins on 14/03/2019 23:01:52:

Good question. This looks like the speed controller **LINK** It seems to run equally well in either direction by swapping the motor leads.

... As you probably kinow to reverse a universal you have to swap just the field or armature.

That's a very bold assumption frown Thanks for the information yes


Thread: Why do both power hacksaws and bandsaws exist?
16/03/2019 23:17:49

My guess is that new technology made flexible blades with HSS teeth a reality and thus suitable for cutting steel at high speed. The reciprocrating saw becomes old and slow technology.


Thread: Tool Post Milling/Drilling Attachment
16/03/2019 19:47:55

I'd considered a spindle like the one Nicholas used. My concern was that there might be insufficient torque to drive a 6mm drill through steel at 1000 or so rpm which is at the bottom end of the speed range for a 12000rpm spindle. I, too, had doubts about the robustness of the bearings. Hence my clumsy looking but workable solution. Happy to be proven wrong smiley


14/03/2019 23:01:52

Good question. This looks like the speed controller **LINK** It seems to run equally well in either direction by swapping the motor leads.

14/03/2019 14:36:01

Being the impatient soul that I am, I have conceived the need for an easily mountable tool that can be used for milling and drilling items held in the lathe headstock. I do this quite a lot with a vertical slide and 95% of the work is done at centre height. This is my attempt at a tool post mounted attachment:







The spindle is based around a pair of angular contact bearings and an ER11 straight shank spindle, both from ARC. The motor is a 200W 230V treadmill unit with speed control from ebay **LINK**

I'm waiting for a pulley cover to print at the moment.



Edit:  I paid £44 for the motor  -  looks like he might be out of stock with speed controllers for the moment.

Edited By Roderick Jenkins on 14/03/2019 14:40:30

Thread: Watchmaker's vertical slide
10/03/2019 16:35:19

It's all becoming clear now. The original designer of the vertical slide was a maker of watches that showed the relevant astrological phase as well as the solar time. Since then Lorch slides are like they are because "We've always made them like that". Mind you, being a Gemini I'm in two minds about this.

Michael: thanks for the link - very useful.



08/03/2019 08:01:12

The most likely rotation for me is from horizontal to vertical which is 22 1/2 divisions which seems "just wrong" but then I'm not a watchmaker 😐

Whatever, I'm trying to design a spindle for it to go on my 1750 Pu!tra.


07/03/2019 21:58:59


I have one of these Lorch type vertical slides, without the milling spindle.


Can anyone hazard a guess as to why (or even actually knows!) the circular scale is engraved 0-90 rather than 0-360 (or 0-36)?



Thread: lathe to cut 26tpi
20/02/2019 22:19:43
Posted by John Duncker 1 on 20/02/2019 21:40:48:

Why was I gobsmacked well it turns out that the leadscrew is imperial but the cross slide and compound are metric

You are in good company - all metric series 7 Myford lathes had 8 tpi leadscrews.


Thread: Myford Dickson toolholder and 10mm tooling
19/02/2019 09:53:49

I've milled the bottom off 10mm tip holders but I don't think this is a fault of the tool holder manufacturers. I imagine that the holder was designed to hold a maximum 3/8" (9.5mm) HSS tool. There is quite a lot of variation with tipped tools, depending on how deep the tip sits in the tool and the thickness of the tip itself, making 10mm tip holders marginal even in original Dickson tool holders. I think 8mm tipped tools are probably a better choice for Dickson equipped 7 series lathes.



Edited By Roderick Jenkins on 19/02/2019 10:04:12

Thread: New coffee maker - disgusting taste!
17/02/2019 16:35:04
Posted by Mike Poole on 17/02/2019 15:57:12:

Absolutely! And the cream goes on first then the jam.


No dogma here please. A proper engineer will determine whether the cream or jam is the more viscous and then apply the thicker of the 2 first, thus enabling consistent layering of the 2 components.



Thread: Potting Adhesives : for Glass Fiber/Fibre Optic Bundles
14/02/2019 08:45:33


When I was scouting around looking for a metallurgical potting compound for home use I plumped for this stuff via Amazon **LINK** It sets hard and doesn't interfere with the grinding and polishing of the specimens. Actually it polishes up very nicely itself and seems very similar to the professional (expensive!) products I used to use in a former life.

Hope this helps,


Thread: print-offable and laminatable chart
03/02/2019 13:01:07


These are from Bradley's Series 7 Manual:

myford imperial.jpg

myford metric.jpg


changewheel setups.jpg



Edit:  Forgot to add the setups

Edited By Roderick Jenkins on 03/02/2019 13:08:04

Edited By Roderick Jenkins on 03/02/2019 13:08:55

Thread: Myford Change Wheels
01/02/2019 20:38:34
Posted by not done it yet on 01/02/2019 20:05:12:
Do you mean you cut them all separately? Or was it one long cut and then parted off?

rolls milling.jpg



01/02/2019 10:41:51


I accept the collective wisdom of the desirability of cutting the teeth in one pass but can somebody please explain to me the mechanism of more than one pass blunting the cutter?

In my case a combination of the power of my mill motor and the slowest speed of my auto table traverse, not to mention the noise from the back gear, led me to be more comfortable with 2 passes and the cutter (which I assume is Chinesium) still seems to be sharp.



Thread: Fitting a Reversing Switch to a Motor on a Myford Lathe
01/02/2019 10:34:34


This scan from The Model Engineer's Handbook seems to show a similar situation to yours although this is a connection diagram for Crompton Parkinson motors.

motor connections.jpg



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