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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: Folding Bike design & build
09/04/2019 19:52:32

That's very neat. As a folding bike owner I appreciate many of the issues you have overcome. What is the transmission system/ratios?



Thread: Natural gas for TIG welding
01/04/2019 11:30:46

Haven't you noticed the date guys 😎

Thread: What Did You Do Today 2019
31/03/2019 19:42:44
Posted by Peter Spink on 31/03/2019 17:50:46:

Do you get any 'flap' with such a long belt?

Belt flap seems well controlled even when working hard. I put this down to very low stretch, good flexibility and good wrap around the pulley ( unlike the round flexithane belt on my new milling spindle, I need to make a bigger belt cover sad)


31/03/2019 17:31:38

Made some pulleys and converted the mill to Poly V. 2 step pulleys and VFD gives top speeds of 2900 or 1160. Beautifully smooth and quiet now, no rattling intermediate pulley or wheezing size A belts.

From ( in the old workshop)



mill poly v.jpg

I also made a top hat washer to centre the draw bar in the spindle bore for better balance at the new higher top speed.


Thread: Advice on Choosing A Mini Lathe
30/03/2019 22:43:38

Perhaps we need to define our terms. Suppliers in both the UK and USA describe 7x12 and 7x14 lathes as mini lathes. I suggest that Sherline and Taig lathes (and Pultra, Flexispeed and Adept) could be referred to as micro lathes.



Thread: DraftSight no longer free
28/03/2019 12:52:25

Just to go back to the original comment for a moment. My copy of Draftsight is copyrighted 2012 and, as far as I know, has no connectivity to Dassault Systems. It is a 2D only version. I don't expect this to disappear. Time. of course, will tell.


Thread: 4" chuck backplate
24/03/2019 14:18:36
Posted by Martin Shaw 1 on 23/03/2019 20:58:03:

...It was also the first time using carbide insert tooling ...

Perhaps not too fast.


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.


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