Machinists Gazette

MANUAL MACHINES => Saws & Grinders => Topic started by: Carpenter84 on June 05, 2019, 08:48:06 PM

Title: Automatic SG
Post by: Carpenter84 on June 05, 2019, 08:48:06 PM
Here's a crazy idea... Anyone ever converted a manual SG into a semi automatic one?

My manual one is a chore to run if I'm doing a large part or lots of grinding. My arms get pretty tired and the hands get pretty out of sync after a while. Haha.

My traverse hand crank can disengage. I know pneumatics much more than I do hydraulics. I figure I should be able to disengage the crank and use a double acting pneumatic cylinder with a switch much the same as the hydraulic. Etc. Then advance back and forth by hand, but at least the repetitive hard work is automatic
Title: Re: Automatic SG
Post by: Terrywerm on June 06, 2019, 12:03:47 AM

Because air is compressible, using a pneumatic cylinder to move the table back and forth would not give you the steady movement that can be had with a hydraulic system.  All it would take is a little stickiness somewhere  on the bed and the table would move in jerks, or at varying speeds, giving you a horrible finish.


Not trying to discourage you, but simply taking a realistic viewpoint.
Title: Re: Automatic SG
Post by: Carpenter84 on June 06, 2019, 12:21:01 AM

Not trying to discourage you, but simply taking a realistic viewpoint.

No no, that's why I post.
I'd have to research what's needed for hydraulic.
Title: Re: Automatic SG
Post by: Terrywerm on June 06, 2019, 12:25:09 AM
Got it.  It probably would not be much more expensive than pneumatic. You certainly would not need a very big pump, but it and it's motor would add to the cost. Additionally, the hydraulic valves would be more expensive than pneumatic ones. Cylinder prices would be very similar for the same size.
Title: Re: Automatic SG
Post by: Carpenter84 on June 06, 2019, 12:39:19 AM
I'm intrigued... It's going on the "list".
Title: Re: Automatic SG
Post by: ddickey on June 06, 2019, 05:44:44 AM
Or some cheap stepper motors. Several have done that conversion.
Title: Re: Automatic SG
Post by: Carpenter84 on June 06, 2019, 06:08:41 AM
What kind of electronics or programming is involved in that?
Title: Re: Automatic SG
Post by: ddickey on June 06, 2019, 06:29:23 AM
I'm not sure. Looks simple enough. Never paid real close attention as my SG would not be a candidate.
Title: Re: Automatic SG
Post by: chips and more on June 06, 2019, 08:19:50 AM
A pneumatic or hydraulic design would be messy. I would do a stepper design. The controller could be as simple as an Arduino. But any project like that can suck up every bit of your time and money. This old fart has learned that it is cheaper to get the surface grinder with the automatics made from the factory! I have a manual SF. It’s like rubbing your tummy and head at the same time LOL. It would be nice to have an automatic but I have bigger fish to catch…Dave
Title: Re: Automatic SG
Post by: 4GSR on June 06, 2019, 08:25:18 AM
It would be real easy to set up a motor controlled by VFD and limit switches in place of the adjustable table stops.  Or have the limit switches ride over a cam on the table.  May have to put a large braking resistor on the VFD.  But hey, what do I know?  Stepping motors would work, too.
Title: Re: Automatic SG
Post by: Carpenter84 on June 06, 2019, 08:39:06 AM
Actually.. I have a small motor that could potentially fit the bill...
It's a geared motor from a small, light weight jib type hoist. My original intention for it was to be my power feed on the mill. That didn't turn out, it's next intention was to replace the hand crank on the column. That still hasn't happened. It's not variable speed, but it's pretty strong. And it reverses direction as fast as you can push the buttons on the remote. I'll have a look at the motor. Maybe it's 3 phase, or DC. Cause a single phase doesn't change direction that fast. But all the components are already there. I'd just replace the remote buttons with limit switches of some kind and some kind of belt/chain connection to the hand wheel. Hmmmmmm.



Edit, this is the best photo of the motor I have in my phone.
Title: Re: Automatic SG
Post by: woodchucker on June 06, 2019, 11:21:31 AM
see this video, might be what you need.
https://youtu.be/FZL9Lqvkqcc
Title: Re: Automatic SG
Post by: Carpenter84 on June 06, 2019, 11:57:16 AM
Oh man!!
I only bothered to watch the first 5 opening seconds of that video and decided that's an excellent idea and already have it designed in my head! Wow. Ingenious!
Way smoother than forwarding and reversing, much easier on the motor. Probably a lot quieter.

I did go back and watch him break down the parts.

I do have quite a bit of room for something like that on the far forward end of the table to house the motor. I would probably simplify the design with just a spider type face plate with a slot to adjust the stroke length, also keeps from having a rotating shaft spinning around to catch clothes, or rags, or whatever happens to be near it.
I love it!
Title: Re: Automatic SG
Post by: 4GSR on June 06, 2019, 01:05:04 PM
That thing would beat you to death if you accidentally got your arm caught in that. I know I would, finding a place to prop up my arm/hand.  WAP!!! there goes your hand! Or something else not mentioned here! :D
Title: Re: Automatic SG
Post by: Carpenter84 on June 06, 2019, 01:50:19 PM
Ya, the adjustment arm is elegant, but not a great design. That's why I figured a round plate with a slot would be more desirable.
Title: Re: Automatic SG
Post by: Bill Gruby on June 06, 2019, 01:59:05 PM
 A round disk with a movable drive pin would be better IMHO.

 "Billy G"
Title: Re: Automatic SG
Post by: Carpenter84 on June 06, 2019, 02:24:41 PM
 .