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WM18 - Z Axis power feed

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petro1head23/07/2019 13:41:41
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606 forum posts
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Would love to have power feed to the Z axis

Someone hear has done it as I have seen the photos however the motor is mounted horrizontally and sticks out a long way.

I would like to do this but have the motor fitted vertically but also still be able to use the handle.

I assume I will need some 1:1 mitre gears.

So, what motor should I buy?

Edited By petro1head on 23/07/2019 13:42:27

Ian Parkin23/07/2019 14:35:07
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dsc00854 (large).jpg

That’s a parvalux geared 24v motor easily available off ebay and with this motor you would have to put a clutch in as you wont be easily overrunning it if you want a manual handle too..why you want a handle?

Edited By Ian Parkin on 23/07/2019 14:36:36

Edited By Ian Parkin on 23/07/2019 14:37:14

Tim Stevens23/07/2019 14:58:50
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1085 forum posts

The device shown by Ian P has a vertical lead screw for the Z movement. This is fitted (originally) with a mitre gear and the handle fits in place of the motor drive shown. So, it should be easy to extend the lead screw upwards (perhaps by a more complex nut) and fit a motor there, the motor having internal gearing to reduce its rpm. This would leave the original handle in place, and it would rotate in sympathy with the motor drive.

Of course, you also need a manual drive, without turning the motor. So, you need a dog clutch between the motor and the lead screw.

The motor you need will be geared down a lot to about 50 - 100 rpm, and the torque at the output wuill need to be rather more than the torque required to turn the lead screw nut in normal conditions. The motor is likely to be specified as output torque at the motor (not including reduction gears) and so many rpm. Knowing this the reduction ratio and output torque needed can be calculated fairly simply. Halve the RPM and you nearly double the torque. 10% of the rpm gives you about 80 times the torque. [It would be 100 times if the gearbox did not add a friction load.] And it does no harmn to have a bit of torque in reserve.

Remember that you must include switches to turn off the motor automatically just before the Z movement gets to the end of its travel. Best to do this first, or you might get carried away with your efforts and try switching on before it is finished ... And another switch which cuts out the motor as you disconnect the clutch.

The voltage you need is not really a serious concern, but - a low voltage motor is much safer than anything on the mains supply. Just chose from what is on offer, bearing in mind it will need a power supply, so 12V seems favourite perhaps using a computer power box. But it must be a DC motor or you will have fun reversing it.

Hope this helps

Tim

 

Edited By Tim Stevens on 23/07/2019 15:00:29

petro1head23/07/2019 15:27:03
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606 forum posts
111 photos
Posted by Ian Parkin on 23/07/2019 14:35:07:why you want a handle?

That the one I saw.

I just thought it would be helpfull for fine adjustment

petro1head23/07/2019 15:30:13
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606 forum posts
111 photos
Posted by Tim Stevens on 23/07/2019 14:58:50:

The device shown by Ian P has a vertical lead screw for the Z movement. This is fitted (originally) with a mitre gear and the handle fits in place of the motor drive shown. So, it should be easy to extend the lead screw upwards (perhaps by a more complex nut) and fit a motor there, the motor having internal gearing to reduce its rpm. This would leave the original handle in place, and it would rotate in sympathy with the motor drive.

Of course, you also need a manual drive, without turning the motor. So, you need a dog clutch between the motor and the lead screw.

The motor you need will be geared down a lot to about 50 - 100 rpm, and the torque at the output wuill need to be rather more than the torque required to turn the lead screw nut in normal conditions. The motor is likely to be specified as output torque at the motor (not including reduction gears) and so many rpm. Knowing this the reduction ratio and output torque needed can be calculated fairly simply. Halve the RPM and you nearly double the torque. 10% of the rpm gives you about 80 times the torque. [It would be 100 times if the gearbox did not add a friction load.] And it does no harmn to have a bit of torque in reserve.

Remember that you must include switches to turn off the motor automatically just before the Z movement gets to the end of its travel. Best to do this first, or you might get carried away with your efforts and try switching on before it is finished ... And another switch which cuts out the motor as you disconnect the clutch.

The voltage you need is not really a serious concern, but - a low voltage motor is much safer than anything on the mains supply. Just chose from what is on offer, bearing in mind it will need a power supply, so 12V seems favourite perhaps using a computer power box. But it must be a DC motor or you will have fun reversing it.

Hope this helps

Tim

Thanks Tim

Good point re switches

Why do you need a clutch, wont the motor just rotate (When there is now poer to it) when using the handle?

Edited By petro1head on 23/07/2019 15:35:34

petro1head23/07/2019 15:39:50
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606 forum posts
111 photos

Here is a VERY rundamentary drawing of what I have in mind

z power feed.jpg

Edited By petro1head on 23/07/2019 15:44:30

Tim Stevens23/07/2019 15:54:30
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1085 forum posts

You need a clutch because:

The motor drive includes a reduction gear which is likely to involve slowing the ouput down by a factor of several. In other words, the motor whizzes round like a fan and the drive rotates sedately and you can count the turns. If the drive is the other way round, you wind the handle slowly but the motor has to whizz round. This makes the drive seriously hard work, if it is possible at all. So, use a clutch to separate the drive and winding the handle will be no more difficult than standard.

The clutch does not need to be fancy - a peg which can slide into a notch will do nicely.

One other thing - it reduces the load on the motor if you can counter-balance the weight of the mill head. In principle - a rope going upwards over a pulley hanging from the roof, and a weight the same as your machine head hanging on the other end. In practice, something more fancy will help to put the dangling weight out of the way. Some users prefer a pair of sliding spring-rods, as used to hold up a hatchback - but finding the right strength is not easy.

If you don't do the counterbalancing, the motor will drive downwards much more quickly than upwards, and this can be disconcerting.

Cheers, Tim

petro1head23/07/2019 15:58:46
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606 forum posts
111 photos

Thanks again Tim, makes sence.

My WM18 has a gas ram for the head making it very easy to raise and lower.

So the motor, still looking and not sure what to get. How much torque will the motor need?

Ian Parkin23/07/2019 16:08:41
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655 forum posts
174 photos

This one would do nicely

**LINK**

and has a right angled drive saving you buying gears

petro1head23/07/2019 16:15:51
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606 forum posts
111 photos

Thanks Ian, output only 7rpm, would that not be too slow? Also how would I attach the handle?

Just to clarify I just want this to move the head up and down and not use it as a power feed.

I did try my corless drill on speed one which is about 400rpm and that seemed perfect

I was looking at somit like this - Link

Edited By petro1head on 23/07/2019 16:21:22

Ian Parkin23/07/2019 16:45:24
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655 forum posts
174 photos

The one i linked is 40rpm but also 7rpm???

i seem to remember mine is 50 rpm (i’m Not able to check until Friday)

suppose it depends how fast you want but i flick the switch and rarely have to wait long till the heads where i need

John Baron23/07/2019 17:29:51
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90 forum posts
16 photos

Anything wrong with pressing a window screen wiper motor into service ? A 3 to 12 volt psu will allow variable speed.

I have a tumbler reverse on mine which gives me a centre off position and allows the handle on the other end to be used.

petro1head23/07/2019 17:50:31
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606 forum posts
111 photos
Posted by Ian Parkin on 23/07/2019 16:45:24:

The one i linked is 40rpm but also 7rpm???

i seem to remember mine is 50 rpm (i’m Not able to check until Friday)

suppose it depends how fast you want but i flick the switch and rarely have to wait long till the heads where i need

From the description:

Working RPM ------------------------------------ 40

Output RPM ---------------------------------------- 7

petro1head23/07/2019 17:50:51
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606 forum posts
111 photos
Posted by John Baron on 23/07/2019 17:29:51:

Anything wrong with pressing a window screen wiper motor into service ? A 3 to 12 volt psu will allow variable speed.

I have a tumbler reverse on mine which gives me a centre off position and allows the handle on the other end to be used.

 

Tumbler reverse?

edit: Like this LINK

Edited By petro1head on 23/07/2019 17:52:07

ChrisB23/07/2019 18:48:02
400 forum posts
162 photos

I'm thinking, why not a stepper motor? You can install it above the column (so its out of the way) and belt driven via timing belt (the timing gear I'd attach to the hand wheel itself. No need for a clutch as there are no reductions in the stepper motor. You can have variable speed as well.

JasonB23/07/2019 19:22:11
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As Tim says, I'd have the motor vertically at the top of the column, either inline with the leadscrew so no need for mitre gears or off set with a toothed belt. That's how the Sieg SX3.5 and SX4 do it.

John Baron23/07/2019 20:13:36
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90 forum posts
16 photos

Sorry Guys, I'm getting confused, I was thinking table feed.

But a wiper motor would still do the job of moving the head up and down.

ChrisB23/07/2019 20:23:38
400 forum posts
162 photos

A wiper motor should work I think, but as it's a geared motor you will not be able to use the handwheel if you need to manually move the head. That's why I would use a stepper,.

petro1head23/07/2019 20:53:22
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606 forum posts
111 photos
Posted by JasonB on 23/07/2019 19:22:11:

As Tim says, I'd have the motor vertically at the top of the column, either inline with the leadscrew so no need for mitre gears or off set with a toothed belt. That's how the Sieg SX3.5 and SX4 do it.

 

So if doing it this way will I still be able to use the handle?  If so I assume I will need to use a stepper motor?

Edited By petro1head on 23/07/2019 20:54:08

ChrisB23/07/2019 20:56:48
400 forum posts
162 photos

If not using a stepper then you'll need a clutch, or someway to disengage a geared motor from the drive.

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