A Project Quest

[Mark_f]

I believe the spider would be better than a hand wheel as I have seen on commercial grinders

 

[Billh50]

I would think that if the table has sufficient over travel the lifting would settle back down before getting to the part for grinding.

 

[Bill Gruby]

The Spider idea came from Grizzly. That price is without the Mag Chuck, add another $765, ouch. Jim, I need a link to those bearings please.

FYI --- 1 full turn of the pinion will move the rack 7.500 inches.

http://www.grizzly.com/products/6-x-12-Surface-Grinder-w-Stand/G5963

"Bill"

 

[JimDawson]

Here ya go

Guide rails...
https://www.zoro.com/linear-guide-rails/c/7511/

Bearings......
https://www.zoro.com/linear-bearing-guide-components/c/7513/

http://www.vxb.com/V-Groove-Bearings-s/235.htm

 

[Bill Gruby]

Thank you.

"Bill"

 

[34_40]

Not sure how I missed this thread for this long... but I'm here now!

On the table "lifting" from the thrust. Would it be prudent (simple) to add a rail to each side to cancel out any lift?
I don't believe it would add much (if any) friction or effort as it should only be in contact in a change of direction for a brief moment.
Or I may be completely out of touch.. LOL..

 

[John Hasler]

I have seen surface grinders with a crank as you describe, but I have never used one. I think they were more production machines rather than tool room machines. I suspect the gear ratio from the crank to table was pretty high so you could get a long stroke with minimum arm movement. Just a guess. I have also seen surface grinders with a lever to move the table.

Here is a picture of the type of ball bearing V-rail I spoke of earlier.

View attachment 128557

I can't see any way that any system involving axles and wheels is not going to be less precise than scraped v-ways.

 

[Bill Gruby]

Welcome all to the dark world of machine design. This is why I invited the entire membership to this project. Every opinion no matter how slight is helping. You are all helping to eliminate trial and error on the part of Mark and myself. Thank you.

"Bill and Mark"

 

[John Hasler]

Not sure how I missed this thread for this long... but I'm here now!

On the table "lifting" from the thrust. Would it be prudent (simple) to add a rail to each side to cancel out any lift?
I don't believe it would add much (if any) friction or effort as it should only be in contact in a change of direction for a brief moment.
Or I may be completely out of touch.. LOL..

Problem is that your rail won't come into contact until the table has already lifted, even if only by a tenth.

It should be possible to design a rack and pinion system such that no lifting force occurs. The price for that might be increased backlash, but that matters little here. Perhaps use a roller-tooth pinion and only allow the rollers to contact the vertical parts of the rack teeth, or maybe just profile the teeth of both the rack and the pinion weirdly.

 

[Bill Gruby]

As Mark has already expressed. the use of open linear bearings and shafts will eliminate all but a very small amount of lift if it were to occur because the table is captured. I'm still not convinced this is our only option though.

"Billy G"