Convert a manual grinder to auto feed?

[JimDawson]

I had not thought about that but I can fully agree. I will have to be sure that I have some form of protection in place.

I would mechanically decouple the motors for hand use, even with them electrically disconnected, there is still an annoying amount of turning resistance and cogging. Some time ago I built a zero backlash 5 pin flex coupler that worked great for the application. A bit of modification to the design would make a great coupler for a surface grinder drive. Just mount the motor on a sliding mount and slide it out of engagement when not in use. I'm going to use this method on my surface grinder when I get around to CNCing it.

 

[Flyinfool]

I was not sure if I wanted mechanical or electrical decoupling. I did not know that the motors have a lot of cogging. I agree, that would be annoying.

So once I figure out what motors I need and can start designing the mounting, I will also be working on ideas for a mechanical decouple.

 

[Flyinfool]

Well I did some checking with my torque meter today. Unfortunately this meter does not go down far enough to check my SG. This meter was bought for measuring in the 200-250 Lb/Ft area, the lowest it goes is to 45 In/Lb. 45In/Lb is equal to 720 In/oz. Most of the stepper motors list the torque in in/oz Now just to get on the scale I even tried yanking as hard as possible in the reversing of direction to get as much inertial load as possible. Still did not make it onto the scale. the only way I could get onto the scale was when I ran it hard against the stops and it still took an uncomfortable amount of pressure to get that reading.

I just did some looking around online and I can not find a resonably priced torque meter for less than $1000 that can measure anything less than720 in/oz unless it is WAY less and to low to be of use. I found one that had a range of 0-18 in/oz.

On the bright side, I guess that means I did a good job cleaning and rebuilding this machine that it moves so freely.

In the x direction just the weight of the handle on the wheel will always have the handle drop to the bottom just from the wheel being out of balance. I may have to add a counter weight to that thing to balance it so that the table can stay where I put it. it is annoying to always have it move to where it wants to go.

 

[JimDawson]

In the x direction just the weight of the handle on the wheel will always have the handle drop to the bottom just from the wheel being out of balance.

This reminds me, you will want to create a method of disconnecting the handwheels when under motor power. You'll break a wrist if that handle comes around and smacks you. My mill has folding handles, but on the grinder you will want to remove the rotating mass of the handwheel.

 

[Flyinfool]

Normally when it is to good to be true, it is to good to be true. So what am I missing in this deal? What is the catch. Seller has a feedback of 2800 and 100% positive.
$32.25 with free shipping, for a kit with 4 each of, 1600 oz NEMA 34 motors, drivers and power supplies and a parallel breakout board?????

Free Ship! 3Axis Nema34 Stepper Motor 878OZ-In DUAL SHAFT Driver DM860A 7.8A CNC | eBay

Dual shaft nema 34 step stepper motor 878oz. Holding torque when DM860A run under high speed is also significantly higher than the other two-phase driver, what’s more, the positioning accuracy is also higher.

www.ebay.com

Yes these motors are way over kill for my grinder, but the 2 extra should be good for either the lathe or the mill later down the road. IS there anything bad that will happen from to big of steppers? Other than just using a lot more power than needed?

If those of you that know more about this than I do (that is almost everyone here) think this is a real deal, I'll jump on a set just to have and call it a start. Then I can start designing parts to make it work.

 

[Flyinfool]

Jim removing the handles is another good point.

 

[JimDawson]

Normally when it is to good to be true, it is to good to be true. So what am I missing in this deal? What is the catch. Seller has a feedback of 2800 and 100% positive.
$32.25 with free shipping, for a kit with 4 each of, 1600 oz NEMA 34 motors, drivers and power supplies and a parallel breakout board?????

Free Ship! 3Axis Nema34 Stepper Motor 878OZ-In DUAL SHAFT Driver DM860A 7.8A CNC | eBay

Dual shaft nema 34 step stepper motor 878oz. Holding torque when DM860A run under high speed is also significantly higher than the other two-phase driver, what’s more, the positioning accuracy is also higher.

www.ebay.com

Yes these motors are way over kill for my grinder, but the 2 extra should be good for either the lathe or the mill later down the road. IS there anything bad that will happen from to big of steppers? Other than just using a lot more power than needed?

If those of you that know more about this than I do (that is almost everyone here) think this is a real deal, I'll jump on a set just to have and call it a start. Then I can start designing parts to make it work.

You can always turn down the power, that's selectable at the drive. I can't figure out if that price is a typo or a closeout sale.

 

[JimDawson]

I just ordered a set, never hurts to have some extra, cheap hardware around. We'll see if I actually get them. I used PayPal for a little extra buyer protection in case things go south. That is really less than the shipping charges.

 

[Flyinfool]

OK, so I ordered one too, they are going fast. Now I also have fingers crossed. Heck the power supplies are worth that if they work.

Debating IF I should order another so that I have enough steppers for the SG the mill and the lathe.........

 

[MikeInOr]

Normally when it is to good to be true, it is to good to be true. So what am I missing in this deal? What is the catch. Seller has a feedback of 2800 and 100% positive.
$32.25 with free shipping, for a kit with 4 each of, 1600 oz NEMA 34 motors, drivers and power supplies and a parallel breakout board?????

Free Ship! 3Axis Nema34 Stepper Motor 878OZ-In DUAL SHAFT Driver DM860A 7.8A CNC | eBay

Dual shaft nema 34 step stepper motor 878oz. Holding torque when DM860A run under high speed is also significantly higher than the other two-phase driver, what’s more, the positioning accuracy is also higher.

www.ebay.com

Yes these motors are way over kill for my grinder, but the 2 extra should be good for either the lathe or the mill later down the road. IS there anything bad that will happen from to big of steppers? Other than just using a lot more power than needed?

If those of you that know more about this than I do (that is almost everyone here) think this is a real deal, I'll jump on a set just to have and call it a start. Then I can start designing parts to make it work.

Don't worry about this add... I just bought the last two.


LOL... that is a good deal and sometimes a good deal does come along. Sometimes a good deal does actually come along WHEN you actually need the item! I will risk the $33 on that. ebay has a good return policy. When things haven't shown up I have gotten my money back in the past.