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Top Slide Self Act?

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Hugh Gilhespie22/10/2011 09:14:34
130 forum posts
45 photos


I want to add a self-act to my top slide.
Why? Well, I have just turned the 4.65 inch radius and put a 15 degree chamfer on the end of the work slide for the Worden T & C grinder I'm making. No problems, mounted on the face plate, turned using a tagential HSS tool but cutting the chamfer was hard work to say the least. Some relevant numbers:
Target surface speed 100 feet per minute
Effective work diameter 9.3 inches
RPM to give 100 fpm 41 - actual 40 RPM
Nice fine feed 0.003 inches per revolution
So, feed rate needed 0.12 inches per minute
Top slide travel to make cut 0.75 inches
Time turning the handle more than 6 minutes.
It doesn't sound very long but it was agonising and I needed to rest my fingers for half an hour after each cut.
As I want to turn quite a few tapers in the near future it seems like a nice idea to fit a self-act to the top slide to make this a lot easier.
I am thinking about a stepper motor driving through a toothed belt. There is plenty of space on the top slide behind the tool post to fit a removeable bracket for the motor and it looks to be straightforward to fit a similarly removable drive shaft to the top slide handle. I need to drive the handle at between 0.5 and say 50 rpm. The upper limit is not crucial and could be less.
I don't want full CNC type control, just a simple stand alone controller for the stepper which will have a pot to set the speed, switch to set forward or reverse and start/ stop switch. I will be quite happy to stand at the lathe watching the dial go around and pressing the stop button at the right time.
Of course it doesn't have to be a stepper but I think it would be hard to find another type of motor with such a wide speed range and I don't want to be fiddling with changing pulleys, gears etc. The attraction to me of this way of doing it is in the simplicity of the mechanical design.
Finally, my question. Does anyone have any ideas, suggestions, information etc about how to impliment a stepper motor for this sort of set-up? Are simple stand-alone controllers available to buy or are there published designs to make one? I would also be very grateful for any input on the size of the motor I would need. I don't have any feel for what a torque rating in Newton cm means in the real world so what size motor will I need?
Regards, Hugh


JasonB22/10/2011 09:30:17
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25215 forum posts
3105 photos
1 articles
Can't you just disengage the handwheel and use a guide along the back of the lathe to move the cross slide just like the majority of taper turning attachments? That way you just use the lathes standard leadscrew.
 
J

Edited By JasonB on 22/10/2011 09:31:24

Clive Hartland22/10/2011 09:54:30
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2929 forum posts
41 photos
Its a good job you did not have to do that job on an ML10. When I made my plate with the chamfer I could not swing the diameter so ended up doing a backwards and forwards in one small quadrant.
I wore a pair of leather gloves and was swing the chuck backwards and forwards for 4hrs. My shoulders and forearms ached for a couple of days.
I was only just able to make the bars for the body as the lathe bed left little room for length.
My Worden is finished now and a great asset to the tool sharpening.
I made adaptors for all the endmills i have both metric and Imperial. Also for the three fluted cutters.
Well worth making the diamond wheel mounting as well.
All I need now is an adaptor to take my saw bench blades and I will be happy.
 
Clive
Gray6222/10/2011 12:24:34
1058 forum posts
16 photos
There is an article in MEW 105 describing a top slide power feed which may help you with your conversion.
 
regards
 
Graeme
Keith Long22/10/2011 16:38:54
883 forum posts
11 photos

I'm with Jason on this one - a taper turning attachment sounds to be the thing you need and relatively simple to make. There have been a number of designs for them in MEW over the years and quite a few available on t'internet. Not suggesting you slavishly copy any of them but adapt the ideas,

Keith

Stub Mandrel22/10/2011 18:00:14
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4318 forum posts
291 photos
1 articles
I use a short piece of allen key hex in the chuck of a variable speed battery drill. It fits in the securing screw for the topslide handle, and its really easy to toddle along at a nice gentle pace using it.
 
Neil
Hugh Gilhespie22/10/2011 19:49:47
130 forum posts
45 photos


Thanks for the suggestions but I don't want to make a taper turner, just some info on stepper motor controllers. I looked at the MEW article by Peter Rawlinson and basically that's exactly what I want. Dead simple and - important for me - easy to make. So does anyone have any suggestions for a suitable stepper controller?
Thanks, Hugh
The Merry Miller22/10/2011 20:37:12
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484 forum posts
97 photos

 
Like your idea Neil, gonna have to try that one out myself.
 
Len. P.
 
 
Nobby22/10/2011 23:13:16
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587 forum posts
113 photos
Hi Neil & Guys

Neils Idea is great . I use this on my Kerry mill drill as well as the top slide for fine feed. A bonus is you can reverse it and use as a rapid as well (GOO that's old hat now?) I used to use a twiddle stick to save my fingers as you can use both hands . Drifting away from the thread a bit . You can fit a strap from the saddle to the tailstock and use it to get feed on your tailstock.

Toolmakers twiddle block that could be another thread

Nobby

Chris Trice23/10/2011 03:22:26
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1376 forum posts
10 photos
I've been toying with making my own power feed attachment for the x axis on my milling machine using a windscreen wiper motor but not sure what the best route for a power source and speed controller might be.
Michael Cox 123/10/2011 08:50:36
555 forum posts
27 photos
Hi Chris,
I made an x-axis feed for my X1 mill using a small chinese dc motor. The feed incorporates an autostop mechanism. The mod is fully described here:
Mike
Chris Trice23/10/2011 10:36:47
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1376 forum posts
10 photos
Thanks for that Michael. That's just what I was looking for. That's a very neat installation. If I get stuck, you may be getting a PM.
geslo06/12/2011 09:25:48
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1 forum posts
Hi Chris
I have also made a powerfeed on my mill.
But I'm using a home made gearbox.
You can see it on my site: www.geslo.nl
Brian Dickinson06/12/2011 10:38:59
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62 forum posts
13 photos
Wow great article Mike i am bidding on a motor gbox just for that purpose for my Warco major mill.
 
 
 
Billy Mills06/12/2011 16:33:03
377 forum posts
Mike has a great number of excellent projects on his site. But to answer Hugh's question-all you need to step a stepper is an oscillator driving a counter which then sequences four transistors, costs a few quid. You could feed a standard stepper driver board with pulses from a 555 timer or whatever. No processor needed.
 
Billy.
NJH06/12/2011 17:06:00
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2314 forum posts
139 photos
Hi Billy
 
Well that's all very well but how about a few drawings and construction details for ex-electronic engineers, like me, whose knowledge and expertise is limited to the analogue era.
OK OK - I know I'm a dinosaur but does that mean I'm eternally confined to twiddling the handles?
 
Cheers
Norman
Hugh Gilhespie06/12/2011 17:41:16
130 forum posts
45 photos
Hi Billy
 
But to answer Hugh's question-all you need to step a stepper is an oscillator driving a counter which then sequences four transistors, costs a few quid. You could feed a standard stepper driver board with pulses from a 555 timer or whatever. No processor needed.
 
Well, yes and no! In a spirit of gay abandon I decided that I would make my own controller. I am now struggling up the near vertical learning curve for PIC assembler programming. I also foolishly decided to try and make an all singing and dancing controller - I think that I will have to drop the dancing though. So far I have a PIC driving a 4 line LCD display that lets you input the lathe speed, desired feed rate and to set a jog rate. I wanted to make it so that you can programme the travel distance as well but have decided that is a step too far.
 
With the lathe rpm and target feed rates set, the PIC then outputs the correct pulse rate to drive the motor. I chickened out of all the stuff about high power mosfets and bought a chinese driver board so all my little PIC board needs to do is send it the pulse rate and a couple of control signals.
 
It has been fascinating doing the programming - I have some experience of Z80 assembler but that was over 20 years ago and now the procedure is so much easier with the Microchip MPLAB IDE - all free too.
 
I have made a small start on the mechanical side and fitted a timing pulley to the top-slide handle but I didn't want to go too far until I was sure that I could cope with the electronics.
 
Regards, Hugh
Les Jones 106/12/2011 17:51:22
2292 forum posts
159 photos
Hi Hugh,
I think this design I found on the web might suit your requirements,
It looks like it came from the "Everyday Practical Electronics" magazine.
The software for it is in the section for the May 2004 issue. (Not the June 2004 issue which you would expect it to be in.)
 
Les.
Spurry06/12/2011 18:40:14
227 forum posts
72 photos
I would second (or third) Neil's advice with the electric drill. I use one with a 3 speed mechanical gearbox on lowest speed. That coupled with the vari-speed trigger covers what I have to do. I find a ball-end hex key in the drill helps a lot.
 
Pete
ady06/12/2011 18:55:22
612 forum posts
50 photos
I am now struggling up the near vertical learning curve for PIC assembler programming
 
lol
I did a couple of years of assembler, it's one heck of a learning curve.
You will find an interpreter invaluable.
Highly addictive and incredibly frustrating to learn
 
This guy made one...the entire microsoft corporation couldn't do it...but he did.
One of the most amazing bits of coding you will ever come across.
 
It's best run on an interface like windowsME or windows98SE, you get far fewer problems.
From windows2000 onwards microsoft was looking to completely remove the reliance on DOS.
The raw power of assembler can completely freak modern versions of windows out.
 
 
While it won't be exactly the same language it shows you the logic with the registers and flags and can help you in many ways, error trapping etc.

Edited By ady on 06/12/2011 19:06:44

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