Surface Grinder Fixed. Figured I'd make something...

[jgedde]

Asd posted here: http://www.hobby-machinist.com/show...r-man-s-Straight-Edge-for-a-scraping-standard I had an issue with my Boyar Schultz 2A618 Surface Grinder that required scraping. Long story short, I completed the scraping and reground the chuck. Got +0.0000/-0.0005 across 18 inches. Good enough for me. Probably not what could have been achieved by someone seasoned in scraping, but I'm content... It was out 0.003!!!

So, I figured I'd make something... The grinder came with several wheels and I had a bunch of W1 on hand. Hmmmm. Could that 45 degree pointed wheel be used for something? Yes! To grind the "rod grooves" for a sine bar (I machined out the majority of the material first). I'd heard that a sine bar is an "exam" for an apprentice toolmaker.

All in all, it took about 3 hours to make (things wen't way too smoothly).

Here it is all done. Almost...



As you can see I didn't go crazy with the grinding on the bottom. Just enough to be flat. The wheel really needed dressing, and I traversed and fed quickly. For the top, I used a carefully dressed wheel, plenty of Crisco for lube and followed it up with about 2 minutes of lapping on 400 grit.

I'm bringing it to work tomorrow to check the calibration, and to use a round wire brush to clean out the oxidation from heat treating the hollow rods. I was too lazy to bring down the gun cleaning kit. I'm sure I'd find a suitable brush in there...

John

 

[churchjw]

Really great project. My skills are not that good yet. Just learning the surface grinder.

Jeff

 

[easymike29]

I've often been criticized for encouraging craftsmen to make their own tools when possible. Good work.
Here's an alternate design for anyone interested.

Gene

 

[jgedde]

I brought the sine bar to work today. The good news is she's flat across the top to within 0.0001. The bad news is that it came in at 5.003 from rod to rod. Granted that's only a 0.06% error, but I had hoped it would be within a thou. I won't affect accuracy if I use the real value of 5.003 instead of 5.

Ya just cant rely on a leadscrew over that many turns to come in exactly where you want it.... I did mark out ahead of time as a sanity check, but it looked OK at the time.

John

 

[DMS]

I recommend a cheap calculator for calculating your stack height rather than a sine table. Much easier/faster; and if you do it that way, who cares if the thing is 5.0000 or 5.0030.

Great work by the way, looks very professional. I do have to take issue with it though, you've got me wondering how I can fit a surface grinder in my shop now...

 

[jgedde]

Turns out I used a dial indicator with its gibs maladjusted. I brought it into the inspection lab and we came up with 5.0008. Still not as good as a Chinese one, but I'm content.

Enco's got an import 5" sine bar for $25 claiming 0.0004 accuracy between rolls.

John

 

[jgedde]

I recommend a cheap calculator for calculating your stack height rather than a sine table. Much easier/faster; and if you do it that way, who cares if the thing is 5.0000 or 5.0030.

Great work by the way, looks very professional. I do have to take issue with it though, you've got me wondering how I can fit a surface grinder in my shop now...

That's how I'd do it (with a calc) anyway even if it came in at 5.0000...

John

 

[owl]

Turns out I used a dial indicator with its gibs maladjusted. I brought it into the inspection lab and we came up with 5.0008. Still not as good as a Chinese one, but I'm content.

Enco's got an import 5" sine bar for $25 claiming 0.0004 accuracy between rolls.

John

Just use it in a 40 degree shop and it should be spot on. Just kidding. Good work.

 

[Rbeckett]

John,
Thanks for another outstanding project. You are a project makin machine!!! Keep up the great work!!!
Bob

 

[jgedde]

John,
Thanks for another outstanding project. You are a project makin machine!!! Keep up the great work!!!
Bob

Thanks Bob, It keeps me sane. I've got new responsibilities at work that I don't particularly care for and are schedule sensitive (read: the pressure is always on). Then, I come home to a house with a mother-in-law and kids who are never quiet. Especially the MIL. She shouts whenever talking to a child. On top of that, she talks non-stop. The shop is a refuge!!!!

The kids come down to visit so I still get time with the young 'uns. )

My wife is VERY patient with my shop time as long as I come up to bed before she's asleep.

John