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View Full Version : Mag Chuck size for 6x12 Surface Grinder??



Henro
01-15-2009, 07:02 PM
Hi,

Well I guess I got the bug...not long ago I just had wood working tools...now I have two SB lathes, a Chinese made smaller size mill/drill, and soon to be delivered Boyar-Schultze 6x12 surface grinder.

But the surface grinder does not have a magnetic chuck...so I am thinking of buying one from CDCO tools (or maybe off ebay, but sort of doubt that).

Question is, while I think the 6x12 magnetic chuck size is what is used normally on a small surface grinder like this, would a 6x18 be unreasonable? I think the table on the surface grinder I bought is longer than 18", and if so I could clamp the longer mag chuck to it.

I am thinking that it might be advantageous to have a longer chuck, for times that non-magnetic work is on the chuck...

How crazy is my thinking? The difference between a 12" long and 18" long chuck is less than $50 delivered...

In the back of my mind, I also wonder if I could use the longer 18" chuck on my mill, if such a need arose in the future. The mill table is 8x32, with about 22 inches travel in the x direction...

Grateful for any insight offered, as I am new to this and just trying to set myself up for a fun time metalworking (as well as woodworking) in a couple years when I retire...

I expect that I will probably go with a 6x12 chuck...

Another question might be, would a 5x12 chuck be reasonable on small grinder? Seems like more of them are on ebay than the 6x12...

Thanks for any and all opinions!

Virgil Johnson
01-15-2009, 07:06 PM
Get the 6x12. You won't be able to grind the 6x18 in even if you could bolt it down.

oldtiffie
01-15-2009, 07:39 PM
Virgil's spot on.

The magnetic chuck will need to be "dressed" - "trued-up" by the grinding wheel - in a single setting.

6 x 12 grinder = 6 x 12 magnetic chuck = 6+ x 12+ between grinder limits/stops - for the wheel ie it must be within the rectangle "swept" by the grinding wheel.

I have a 6 x 12 and a 5 x 10 magnetic chuck - bought new.

I can pretty well assure you that the chucks will have to be ground to suit your grinder such that the chuck sits dead flat on the grinder table and that the top face of the chuck is very precisely flat and parallel to the grinder table ways/guides. Unless you have "true-d up" the face of your grinder table, you will have to re-locate the magnetic chuck very accurately to where it was initially dressed so as to maintain accuracy.

I checked my tables on my 2 T&C grinders and my surface grinders - bought new - and all Chinese - and if there was any deflection on a good TDI I couldn't see it so I left them as is.

My magnetic chucks were both in need of "grinding-in". One was a couple of thou out but the other had a 30 thou warp/twist in it. But I expected to have to grind them in - which I did. There has been no measurable "movement" in either table since - both are excellent.

I ground mine in by putting the top face of the chuck down on grinder table, packed/shimmed it so that there was no movement and that diagonally opposite corners of the bottom face of the chuck (facing upward) were within a couple of thou of each other. I switched the magnets on to barely hold the chuck on the table so as to minimise and distortion it might cause.

I started to grind the base of the chuck - slowly - with a previously dressed wheel (as coarse as I could use to get a satisfactory finish - until I had just the barest "witness" left after a light finishing cut - after the chuck had cooled to room temperature.

I reversed the chuck, clamped it to the table and ground-in the top face as before.

I check my magnetic chucks for "flat" with a good dial indicator each time I mount it on the grinder if real accuracy is required - just in case. If it needs re-grinding I do it - but so far I haven't had to as the chucks stayed remarkably flat and stable.

I can swap the chucks between grinders and I am very pleased with them as I have no need to re-grind if I put the T&C chuck on the surface grinder or vice versa.

Grinding on a magnetic chuck requires a lot of care. They are usually very safe and reliable, but carelessness or thoughtlessness can have so quite surprising and unfortunate consequences.

Take care, good luck and enjoy your grinding.

Henro
01-16-2009, 03:08 PM
Oldtiffe and Virgil Johnson,

Thank you both for the input. That makes a lot of sense!

I appreciate your taking the time to get my head going in the right direction!

It is a huge help. If anyone else has some pointers I would appreciate them too...

Thanks again!

Carld
01-16-2009, 04:07 PM
I would wait untill I have the grinder and find out what the table travel really is. If you can travel over 18" then get the 6x18, if not get the 6x12. I have an Enco mag table and it works fine for me.

Peter N
01-16-2009, 04:15 PM
My grinder is 6"x18", and it has a 6"x18" mag chuck.

However, if I had the choice I would go for something slightly smaller like the 6"x14" chuck that Eclipse made, or perhaps a 6"x12".
The reasoning is quite simple - sooner or later you will need to grind something that needs to hang over the edge of the table at one (or both) ends, and this is possible with the smaller chuck, but obviously not so easy with the larger one.

These grinders are for relatively small-ish stuff, so you don't really, or very rarely, need a chuck that matches the whole table travel.

Peter

aboard_epsilon
01-16-2009, 05:32 PM
an old post of mine

may help

shaper went to the scraper in the end because of cracks found in main casting .....

Progress today
My eighteen inch surface grinder was just able to do nineteen inches...with the centres of the spindle going clear over the ends of the ram.

First the top was surface ground using bottom as reference

http://img.photobucket.com/albums/v190/aboard_epsilon/royal2/top.jpg

Then the bottom was ground using top as reference

http://img.photobucket.com/albums/v190/aboard_epsilon/royal2/bottom.jpg

all the best......mark

Sparky_NY
01-17-2009, 06:50 AM
I bought a boyar schultz challenger 6x12 a couple years ago, also with no magnetic chuck. Someone (here I believe) told me of a internet company that had fine pole 6x12 chucks for $150 (as I recall). That was a great price and I ordered one and have been happy.

As for getting a chuck, get a fine pole if you can find one reasonably. The fine pole type hold small parts better which is what us home machinisits mostly do.

Circlip
01-17-2009, 08:22 AM
Question Mark, (Sorry, no pun intended) How does the axis of the bore and end face in the end of the ram now line up with the top and bottom ??

Regards Ian.

aboard_epsilon
01-17-2009, 08:44 AM
To Ian

That ram is just going back and forward in a horizontal strait line .....you could have the bore pointing off to the other side of the room ..and it would still go back and forth .. and cut in a strait plane.

The flange on the end was checked on a surface plate though..and was found to be very good ..no deviation on the verticle...not that it mattered.

what's inportant is the the ram goes back and forth exactly parallel with the cube on the front.

all the best.markj

oldtiffie
01-17-2009, 09:20 AM
To Ian

That ram is just going back and forward in a horizontal strait line .....you could have the bore pointing off to the other side of the room ..and it would still go back and forth .. and cut in a strait plane.

.................................................. ..
.................................................. ....

all the best.markj

Thanks Mark.

Yup - common practice to "off-set" long grinding runs - say 10>45 (please yourself) to reduce the length of continuous cut. I regularly do it as the job doesn't get so hot. It is all job-dependent though. I use as coarse a wheel as I can to suit the job - much the same reasons.

aboard_epsilon
01-17-2009, 09:27 AM
Thanks Mark.

Yup - common practice to "off-set" long grinding runs - say 10>45 (please yourself) to reduce the length of continuous cut. I regularly do it as the job doesn't get so hot. It is all job-dependent though. I use as coarse a wheel as I can to suit the job - much the same reasons.

Yeah know about that ..I was answering his question of the relationship of the bore where the clapper box bolts onto ...and it being dead on to 90 degrees to the horizontal plane of the newly ground ram slides.

Circlip
01-17-2009, 11:52 AM
Yes Mark, my only concern is when you tilt the the cutter box for doing slopeing cuts, is the machined bore axis still parallel to the top and bottom faces?

aboard_epsilon
01-17-2009, 12:14 PM
Either you are getting me out of my depth ..and you know something i don't ..or I'm just stupid and thick ..

The cutting tool tip ....will...and should always follow parallel to the ram...no matter how cockeyed the clatter box is mounted.

Like i said the whole thing went to the scrapers ...and i didn't really get to study the machine in depth ..lost interest ..when i found the cracks hidden under new thick primer.

So basically Ive not used one ...and cant imagine ...other possibilities of clatter box bore, that would make it cut incorrectly....cause I'm not familiar.

all the best.markj

Circlip
01-17-2009, 12:44 PM
No on all derogatory points Mark, the bore is/should be square and parallel to the front face and o/d of the boss on the ram, so providing the machined face on the front of the ram is still at right angles to the slides it should be ok. You can check by putting the ram on a surface plate and slide a square with the leg vertical (No,the leg on the engineers square) up to the face of the boss.

Regards Ian.