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mini overhead drive - opinions please

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Ady112/10/2012 02:33:32
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3462 forum posts
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Just a mock up of an idea I had an hour ago

I've got a good lathe and motor and would like to run various attachments from it

I don't want a massive unit, just something which will power any bits and pieces I make for the cross slide

The motor will power the pulley on the lathe spindle with the bullgear disengaged and the backgear disengaged, so the spindle pulley runs independently

and the pulley will power the overhead drive via some good quality 5mm lathe belting

If this works out it means I don't need to bother with any additional electric motors to power my gizmos and attachments

The bits will be angle iron and 12mm rod from B+Q and bearings from fleebay

Michael Gilligan12/10/2012 09:53:11
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Ady,

From your picture, it was apparently one of those "light-bulb" moments.

Seriously though:

The idea is very sound, provided that the speed range is what you need.

Generally speaking, it is more convenient to use a dedicated motor to drive the Overhead; and it can be easily arranged that the weight of that motor tensions the belt. There have been several designs in Model Engineer, and J. Malcolm Wild nicely illustrates design and use in his book.

MichaelG.

 

Wheel and Pinion Cutting in Horology

Edited By Michael Gilligan on 12/10/2012 09:56:28

Clive Hartland12/10/2012 09:57:29
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Schaublin had a similar set up where the milling tool holder was clamped on the slides and the drive was taken from the headstock. Indexing allowed maching of different shapes.

The overhead gantry was spring supported to keep belts taut. It was only used for small scale jobs and would not machine large objects at all.

Clive

Michael Gilligan12/10/2012 10:05:18
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12687 forum posts
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Ady,

It's worth a look at this page

MichaelG.

Ady112/10/2012 10:06:31
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I found a place where a chap made a small one which includes what look like self tensioning jockey wheels

Not part of the lathe, but the same sort of thing

Ady112/10/2012 10:25:34
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3462 forum posts
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The overhead gantry was spring supported to keep belts taut. It was only used for small scale jobs and would not machine large objects at all

This is going to be the real challenge IMO, transmitting torque

Modern lathe belting is amazingly strong and reliable nowadays which will be a big help

For milling and drilling I have an old cowells lathe headstock with full backgear to experiment with

Ady112/10/2012 10:44:19
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3462 forum posts
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Generally speaking, it is more convenient to use a dedicated motor to drive the Overhead; and it can be easily arranged that the weight of that motor tensions the belt

Instant solution number 1

I will drive the overhead directly from the motor with the 5mm belting

It can be removed when not needed

Will take a while to do it right, but it looks like this could be well worth a go

Ady112/10/2012 11:34:15
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3462 forum posts
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There's a couple of reasons

The original motor can happily run all day doing higher torque work, even my good old bosch drill is starting to give up the ghost from hole drilling in the press. Modern electric motors don't like being worked too hard

I don't want to be messing about with different electric motor mountings and fitting them onto individual gadgets around my cross slide and headstock

I would much prefer to have a simple belt pulley on each gadget where I snap on a small belt and it runs all day if required

This also means I have loads more room for the gadget, there's no motor setup in the way, only a small belt to the overhead drive

If I can sort the torque issue then I can do all sorts of things like a small power slotter for making gears with the workpiece in the headstock as an indexing tool

edit:

Finally, for whatever reason this kind of stuff pushes my buttons because it provides multiple solutions

Longer pieces can also be indexed and worked on along the length of the lathe, the old M series is an extremely strong stiff unit

If the job gets too tough the belting will slip, there's no more motor burn-out issues on these one-off big jobs we occasionally run into, so you can focus on solutioning the machining problem

Edited By Ady1 on 12/10/2012 12:06:05

Michael Gilligan12/10/2012 13:37:00
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12687 forum posts
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Definitely a useful project, Ady ... Please do share your findings.

By the way:

It's probably also worth having a look at the kit used by Ornamental Turners.

MichaelG.

NJH12/10/2012 14:50:25
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2313 forum posts
139 photos

Ady

I guess that could be a useful facility. My only concern is with all that stuff without any guarding whizzing around above the lathe. Be sure that, in your enthusiasm to see what's going on, you keep your hair, beard, ears etc well away from the moving bits!

N

Edited By NJH on 12/10/2012 14:51:48

Ian S C13/10/2012 10:47:48
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7220 forum posts
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One source of cheap low voltage motors is discarded battery drills, the batteries give up, the drill gets throwen out, because the replacement battery costs more than the machine is worth. I'v got a low voltage power supply in the workshop, and I,v got an 18V drill wired into that, with a bit of work, that could be mounted on the lathe. Ian S C

Terryd13/10/2012 11:08:56
1926 forum posts
179 photos
Posted by Michael Gilligan on 12/10/2012 13:37:00:

Definitely a useful project, Ady ... Please do share your findings.

By the way:

It's probably also worth having a look at the kit used by Ornamental Turners.

MichaelG.

Hi Michael,

This type of machine and work, including Rose Engines and Guilloche work was discussed in this thread.

I suspect that Ady might have got a bit of inspiration from these references wink 2

Terry

Bazyle13/10/2012 11:30:36
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4390 forum posts
184 photos

Seems perfectly reaonable and workable. I would just caution keeping a good eye on the lubrication of the pulley block running on the main spiindle as the bearing setup is not too good.

AndyB13/10/2012 12:42:13
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167 forum posts
7 photos

Hi Ady,

I have often thought about the same thing because of the Drummond attachments available (from the same shop as hen's teeth).

Could you mount the overhead on the wall behind or on the back legs of the stand (if you have one)? That would give you an angled drive towards the back to keep it away from your face.

The shaft can run in Plummer Blocks. Keep the motor low so you get tensioning capability and good grip for the drive belt from a long run.

Tony Griffiths has solid round drive belting that is very easy to join (just done it for a sensitive drill).

I could do the same as I have rafters just above my lathes...just never got round to it...yet.

Andy

Edited By Andy Belcher on 13/10/2012 12:45:02

Terryd13/10/2012 13:03:21
1926 forum posts
179 photos
Posted by Andy Belcher on 13/10/2012 12:42:13:

Hi Ady,

I have often thought about the same thing because of the Drummond attachments available (from the same shop as hen's teeth).

Could you mount the overhead on the wall behind or on the back legs of the stand (if you have one)? That would give you an angled drive towards the back to keep it away from your face.

The shaft can run in Plummer Blocks. Keep the motor low so you get tensioning capability and good grip for the drive belt from a long run.....................


Andy

Edited By Andy Belcher on 13/10/2012 12:45:02

Hi Andy,

The shaft should not actually rotate, it is there to act as a sliding axle for the pulleys which carry the belting over it if a seperate electric motor is used. The pulleys are allowed to run free and slide along the shaft so that the drive can operate different devices at different positions along the lathe bed.

On the original ornamental lathes where this is a necessary part of the lathe (see links above) the shaft is driven, but by a pulley drive from the lathe drive i.e. a treadle operated flywheel.

A better solution for Ady, if he is using an electric motor for the drive may be something like this below which can be bolted to the bench or perhaps the end of the lathe bed. It would be fully adjustable and can easily be moved out of the way when not needed.  A great deal of torque is not needed for such as a toolpost drilling machine or grinder, speed is more important.

overhead drive.jpg

Just another approach,

Best Regards

Terry

Edited By Terryd on 13/10/2012 13:06:26

AndyB13/10/2012 13:47:40
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167 forum posts
7 photos

Hmmm...

I hadn't thought of that way. Nice one Terry.

I thought of a shaft running the length of the shed with cone pulleys (adjustable speeds) positioned above the lathes for use on all of them (there are actually 3 in a line now... an S7, a standard M and a long bed M to replace the long bed B...yes I know, I'm a magpie).

No point in collecting if you don't use them...

Andy

Terryd13/10/2012 15:57:23
1926 forum posts
179 photos

Hi Andy,

As a point of perhaps interest, somewhere I have a picture of the metal workshop at Rugby School (yes, the posh public school where Rugby football was invented) taken sometime earlier last century. In those days it was quite a desireable part of education for sons of the gentry and nouveau riche due to the impetus of the Industrial Revolution and the amateur inventors (who were all rich). After all a Hotzapffel ornamental lathe with all available accessories cost about the equivalent of one and a half substantial homes - no inexpensive Chinese stuff at that time - so it was a very rich man's hobby.

The picture shows all of the machines in the school workshop and it all was all driven by overhead shafting and belts, so it was not just common in factories. There is also a class of boys working with no safety devices in sight. I'll publish it here when I can find it.

Regards

Terry

Clive Hartland13/10/2012 17:01:08
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2396 forum posts
38 photos

The overhead drive shafts were quite common when I went to Tech. School in the 50's , One big electric motor drove the system and cross over belts were used to engage the drives to the machines. I can still remember the , 'Slap, Slap' of the belting.

To my memory the shafting drove 3 Lathes , a shaper and a Horizontal milling machine. Maybe a big drill also.

I used to quit History and Physics to work in there and the teachers would try to get me to go to their classes but after a time they did not bother anymore. In any case i quit school at 14 to join the army so it did not matter anyway.

Clive

Stub Mandrel13/10/2012 17:11:37
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4306 forum posts
291 photos

Ian's suggestion of using a portable drill motor is interesting, but they need a high-current drive. I made a steel gear-case for the epicyclic gears from an old drill to make a toolpost mill/drill. You need a good 4 or even 8 Amp power supply at 12 to 18 volts to get decent results. A car battery might be agood solution?

Neil

Ian S C14/10/2012 11:50:32
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7220 forum posts
227 photos

When I was at Tech collage in Dunedin in the early 1960s, the workshop there was almost entirly run from line shafts, must have been a dozen big old Harrisons, and some Colchesters, shapers and mills, and drill presses. I think the only self powered lathe was the Chipmaster. Origionally the workshop was powered by a steam engine, but in latter years a large electric motor took over. No one seemed overly concerned about the open belts, and they seemed to instill an industreal feel to the place. Ian S C

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