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minilathe speed reduction

pulleys

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Michael James 525/08/2018 19:08:26
22 forum posts
Just wondering if anyone has come across pulleys -driven one- which I can use to reduce the top speed of an Amadeal cj18a.2500 rpm is ridiculous for me and even with the new brushless motor a bit more torque would be useful .I ve looked everywhere but only pit luck so far in one that fits the belt .Thank you very much
oldvelo25/08/2018 21:13:33
155 forum posts
43 photos

Hi Micheal

Perhaps new fabricated pulleys using "Poly Vee Belts" can be made to fit in place of the originals.

Now assuming that this head stock has a two speed gear box and belt drive then increasing the belt drive ratio then increases the load on the somewhat flimsy gears breakage is a lot more likely.

My hobby over the last few years has been renovating repairing workshop machines and re powering with mainly DC Motors.

A bigger motor or increase the drive ratio to increase torque at the spindle with a loss of top speed.

Eric

Michael James 525/08/2018 21:31:22
22 forum posts
Thank you Eric.I thought new belt and pulleys might be it- a v belt wouldnt slip?Its a metal geared lathe so they d bettet not break!
Michael Gilligan25/08/2018 21:37:04
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Posted by Michael James 5 on 25/08/2018 21:31:22:

Thank you Eric.I thought new belt and pulleys might be it- a v belt wouldnt slip?

.

Michael,

Poly Vee Belts are much better performing than the conventional vee belt.

... at this size you could probably use 19mm motor pulley.

They've changed the rules of the game !!

MichaelG.

.

I see that the standard drive is via 'timing belt'  ... What count are the pulleys ?

https://www.amadeal.co.uk/acatalog/CJ18%20Manual.pdf

Edited By Michael Gilligan on 25/08/2018 21:55:29

Michael James 525/08/2018 22:37:22
22 forum posts
31 for tbe driven pulley
I assume it would be best to change that a size smaller or the motor pulley would be tiny.Not sure what the count is on that yet
Michael James 525/08/2018 22:39:02
22 forum posts
Found it.motor pulley 18 teeth
Michael Gilligan25/08/2018 22:45:19
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13556 forum posts
586 photos
Posted by Michael James 5 on 25/08/2018 22:37:22:
31 for tbe driven pulley
I assume it would be best to change that a size smaller or the motor pulley would be tiny.Not sure what the count is on that yet

.

31 ... That's surprisingly low [to me, at least]

Whilst you are checking the motor pulley, could you please also let us know details of the belt [hopefully marked on it]

I'm sure the team can come up with some suggestions

MichaelG.

.

Edit: that was quick !! 

Let's dicsuss tomorrow.

Edited By Michael Gilligan on 25/08/2018 22:47:42

Michael James 525/08/2018 23:05:33
22 forum posts
Ok Nichael.thank you very much
JasonB26/08/2018 07:25:00
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15750 forum posts
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If the metal gears won't give way then something else like the control board will be the next down the line.

Also if you go much smaller that 18T on the motor you may have a job getting the belt to grip without chewing off the teeth. You want to go bigger on the driven pully not smaller to reduce the speed.

Edited By JasonB on 26/08/2018 07:29:08

Michael James 526/08/2018 08:24:18
22 forum posts
Good morning Michael
motor pulley avtually 17 teeth/8 mm bore
driven belt 10mm bore/ 31 teeth
belt marked 1.5 x 70/ 70 cogs.
The bores and keyways I can do myself .
Michael James 526/08/2018 09:57:55
22 forum posts
Hallo Jason
Getting my pulleys mixed up!
I was thinking of doing this not really to use the lathe harder,although I suppose thats inevit able,but to save replacing motor/ circuit board.Its quite a powerful motor for what I do anyway so I should perhaps have asked first' Is thos worth doing?' perhaps its not!
Michael Gilligan26/08/2018 10:09:34
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13556 forum posts
586 photos
Posted by Michael James 5 on 26/08/2018 08:24:18:
Good morning Michael
motor pulley avtually 17 teeth/8 mm bore
driven belt 10mm bore/ 31 teeth
belt marked 1.5 x 70/ 70 cogs.
The bores and keyways I can do myself .

.

That's great, Michael ... it confirms what I found on the Amadeal site:

 

img_2199.jpg

Here's an extract from the manual that I linked ^^^

What Eric and myself are proposing is to replace the two timing pulleys (27) & (148) with Poly Vee.

... I feel quite comfortable that 3 or 4 rib J section belt would work very nicely, and you could easily get a high reduction ratio in the same space as the existing arrangement.

An incidental advantage is that a poly vee belt can be tensioned such that it will slip before the gears fail yes

MichaelG.

.

Edit: useful references to the original parts

https://www.amadeal.co.uk/acatalog/Drive-Pulley-for-CJ18---Part-27-533.html#SID=268

https://www.amadeal.co.uk/acatalog/400W-motor-for-CJ18A-Mini-Lathe-AMA_SP_CJ18_150_400W.html#SID=240

https://www.amadeal.co.uk/acatalog/Timing-Belt-AMA_SP_CJ18_029RB.html#SID=198

https://www.amadeal.co.uk/acatalog/CJ18-Metal-Gears-Set-AMA_SP_CJ18_2418MGRB.html#SID=11#SID=11

Edited By Michael Gilligan on 26/08/2018 10:22:05

Vic26/08/2018 11:37:04
2172 forum posts
10 photos

The very first job on my lathe years ago was to machine the smallest pulley I could to reduce the speed of my lathe for single point threading. I managed to get the lowest speed down from 180 rpm to about 100 rpm. The pulley is still on the lathe, I never put the original back although I still have it.

blowlamp26/08/2018 11:49:48
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1196 forum posts
82 photos
Posted by Michael James 5 on 25/08/2018 19:08:26:
Just wondering if anyone has come across pulleys -driven one- which I can use to reduce the top speed of an Amadeal cj18a.2500 rpm is ridiculous for me and even with the new brushless motor a bit more torque would be useful .I ve looked everywhere but only pit luck so far in one that fits the belt .Thank you very much

Your lathe has a brushless motor?

Michael James 526/08/2018 13:28:59
22 forum posts
Yes brushless motor.
I shouldnt worry about vircuit boatd either as a v belt can be tensioned to slip before too many revs are lost too..This is fascinating!
blowlamp26/08/2018 14:19:07
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1196 forum posts
82 photos
Posted by Michael James 5 on 26/08/2018 13:28:59:

Yes brushless motor.

I shouldnt worry about vircuit boatd either as a v belt can be tensioned to slip before too many revs are lost too..This is fascinating!

They should advertise it better, because I can't see it on their website.

Dunc26/08/2018 15:48:49
127 forum posts

Here are a couple of ideas:

http://mikesworkshop.weebly.com/speed-reducer.html

http://www.toolsandmods.com/lathe/mini-lathe-motor

Many more by googling mini lathe speed reduction

SillyOldDuffer26/08/2018 16:39:05
4529 forum posts
971 photos
Posted by Michael James 5 on 26/08/2018 09:57:55:
...
so I should perhaps have asked first ' Is this worth doing?' perhaps its not!

As always depends on what you're doing with the lathe. But, as small lathes often turn small diameter parts, 2500rpm isn't ridiculous, even less so if you use carbide.

When I had a mini-lathe I would mostly use low gear (up to 1200 rpm) for anything over, say, 20mm diameter, and high gear (up to 2500rpm) for anything less than about 20mm diameter. I prefer carbide inserts which work better at higher speeds. Low rpm is essential for threading under power, which might make smaller pulley attractive. However, I used a spindle handle for threading on a mini-lathe and found manual threading easier to control all round.

Brushless lathes are still a relative novelty. Yours is the first brushless mini-lathe I've heard of and it's performance is likely an unknown quantity due to lack of experience with them on the forum. I'd expect it to be better than a conventional DC motor but not wildly so. Personally, I'd spend some time getting used to the machine before rushing to modify it. Sod's Law says you discover you need 2500rpm just after going to a lot of trouble altering the pulleys!

If you feel the lack of torque, beware you're not overdoing it. Mini-lathes aren't industrial metal munchers that can be pushed to the maximum. Think Fiat 500 rather than Humvee.

Dave

Neil Wyatt26/08/2018 17:23:41
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16257 forum posts
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Posted by SillyOldDuffer on 26/08/2018 16:39:05:

Brushless lathes are still a relative novelty. Yours is the first brushless mini-lathe I've heard of and it's performance is likely an unknown quantity due to lack of experience with them on the forum.

Cor Dave, you aren't paying attention! The earliest mention of the SIEG SC3 (brushless mini lathe) I can find on this forum is April 2011....

Neil

SillyOldDuffer26/08/2018 18:24:06
4529 forum posts
971 photos
Posted by Neil Wyatt on 26/08/2018 17:23:41:
Posted by SillyOldDuffer on 26/08/2018 16:39:05:

Brushless lathes are still a relative novelty. Yours is the first brushless mini-lathe I've heard of and it's performance is likely an unknown quantity due to lack of experience with them on the forum.

Cor Dave, you aren't paying attention! The earliest mention of the SIEG SC3 (brushless mini lathe) I can find on this forum is April 2011....

Neil

Just like being back at school! I didn't pay attention back then either...

Please don't tell mum I've been caught daydreaming in class again. She still thinks I'm wonderful.

smiley

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