Boyar-Schultz 612 surface grinder belt conversion WIP

Worked on the lathe today. Started with the upper spring perch. I didn't takes any pictures while making it but I will post a drawing when I wrap this all up. Here's how it looks mocked up.

Untitled by Ranger_Bob, on Flickr

Next up was the idler/tracking wheel. I reversed the 2-piece jaws on my chuck to hold the 4" billet by the O.D.. I faced the front side as shown.

Untitled by Ranger_Bob, on Flickr

Then center drilled.

Untitled by Ranger_Bob, on Flickr

I then drilled with a 5/16" twist drill then stepped up to a 1". I then bored the recess .500" deep leaving a .500" lip to allow chucking the wheel for boring the other side.

Untitled by Ranger_Bob, on Flickr

Bearing pocket bored next. 1.375" diameter by .446" deep resulted in a light press fit.

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Front of wheel complete.

Untitled by Ranger_Bob, on Flickr
 
To do the back side I flipped the jaws back around and clamped to the inside of the lip. I needed the outer faces of the bearings to be 1.375" apart. since I knew my front bearing was set flush with the inner face I needed to face off .124" on the back side of the wheel.

Untitled by Ranger_Bob, on Flickr

After boring for the bearing, I turned the O.D. of the wheel using a 1-degree chamfer just to help with tracking. Done with this.

Untitled by Ranger_Bob, on Flickr

Next I turned and threaded a tapered handle.

Untitled by Ranger_Bob, on Flickr

Here's my home made concave turning tool putting a dish in the end of the handle.

Untitled by Ranger_Bob, on Flickr

I then painted everything and put it all together. All I have left is to weld the outer tube to the clamping collar and paint the bottom. Almost there!

Untitled by Ranger_Bob, on Flickr
 
Looking forward to seeing it completed and seeing what type of tolerances this is capable of. Super cool.
 
Finished it!! It runs really smooth.

Heres what I did today. First thing I did was turn down a heavy ring that I could clamp to so when I weld to the collar, it won't deform. I didn't want to weld it while clamped to the machine because you never know what kind of damage the welding heat will do to seals.


Untitled by Ranger_Bob, on Flickr

Ok, full disclosure here, I made the outer tube too short. The center-to-center distance of the two wheels needed to be 28-1/4" while under tension with the belt mounted. Though I thought I had cut the tube long enough that I would be able to cut to length at the end, it ended up being about 3/8" too short. After thinking about this over night, I decided a spud shaft would be a good idea. I would be able to slip the tube over the shaft while on the grinder and determine perfect alignment and length. In this photo, I am welding the spud shaft to the collar. The ring from the previous photo is clamped in the center of the collar.


Untitled by Ranger_Bob, on Flickr

Here is the way it went together with the tube slipped over the shaft and welded in place.


Untitled by Ranger_Bob, on Flickr

Completed, installed and test run. It is smooth and quiet. No vibration whatsoever.


Untitled by Ranger_Bob, on Flickr

I ran a couple pieces of mill finished 440c with a 60grit and a 220 grit. The only issue I am having is the split edge of the belt causes a slight gouge due to the loose abrasive material. I need to figure out a way to prep the belts after splitting them. I am splitting the belt with the USA Knifemaker splitter.

I will try to get a video up but it will be a week or so since I am heading out tomorrow for Johnny Stout's class. When I get back I will also work on final drawings for the rest of the components.

Bob
 
Great thread, thanks for taking the time to share!

You might try "killing" the edge of the belt with some scrap metal to avoid the gouging.
 
Great work. Thanks for sharing! I'm going to be doing my surface grinder conversion this week and your thread has given me some good ideas. :thumbup:

What HP is your motor and how deep are you making your passes? I'm replacing the stock motor on mine with a 3HP motor +VFD so I can really hog off material when I taper tangs on hawks.
 
Thanks guys! I forgot to mention that I had to go back to the lathe and remove the crown I had in the tracking wheel. It just didn't work right. Tracks super accurate with the wheel flat though. I think my motor is 3/4hp. I have run a 60 grit Blaze and was able to take .003" DOC with a .200" stepover and there was no heat in the steel. I think I could push for more but will take my time seeing what the limits are. One thing I noticed is that there is ramping on the edges of the steel where the wheel comes on and goes off. A harder wheel would probably help (mine is a 70a) but, I think it would be an issue with pushing for deep DOC no matter what.

Bob
 
Bob,

Thanks for the reply. My grinder will be running 2in belts on a 90 duro wheel. My goal is to get .01 per pass with a 36 grit ceramic belt. I will be running wet with Koolmist to avoid heat build up. Hopefully with a 3HP motor running wide open I can get some significant hogging done quickly.

If my grinder conversion works out as well as I hope it will I might have to look into getting a bigger model. I've got a plan to use shims to grind out kitchen knives but I'll have to see how that goes. The extra space a 6x18 machine would provide could really open up the doors for some cool projects like repeatable full length tapers on choppers or maybe even grinding bevels on my machetes. Needless to say I'm pretty excited:thumbup:
 
Is there a reason that many of the belt conversions are made for I inch belts? Would a standard two inch belt cause a problem? ( with 2 inch drive wheel and tracking wheel) The machine work that Bob does looks perfect though so I am sure he thought this out.
 
*****blinks*****

*****blinks again*****

That's gorgeous......................

Once I'm mobile again I'm going to do this same exact thing to my own Boyar Schultz 612. It's not as pretty as Bob's but maybe I'll spiff it up along the way.

Thanks again (and again and again) for taking the time and effort to detail how you accomplished this conversion. I don't own a lathe or mill big enough to make some of these parts and my welding is sketchy at best but I have access to a garage fab shop where I can use the tools to make what I will need and it will be fun.

Corey
 
Watching this excellent conversion, Thank you again, and not have the Lathe etc you do to turn my own wheel and weld etc I realized that I could buy the top part from one of Norman Coots's grinders and use that as a idler wheel & arm to do the conversation.

Anyone interested. go here. www.cootebeltgrinder.com I'm sure Norman would even get a kick out of what I was doing with the tower arm & wheel.
 
That is a beautiful surface grinder and your conversion looks very well executed! I have an almost identical 6x18 grinder, also 3/4kw motor and the exact same wheel size. 150x25mm

With a 36 grit ceramic belt I can take off 8/100mm in a pass. The stone was able to do 2/100 maximum.

2rwwc41.jpg
 
I just spent the last two days doing a bunch of grinding on this and figured I would bring up a couple of thoughts I've had. This thing works great! I can run two passes at about .005" DOC with .200" stepover using a 60 grit blaze belt and the mill finish is gone. One of the things I learned down at Johnny Stout's is that the 3M Trizact belts are all manufactured to the same thickness regardless of grit. This is nice on the SG if you are going to step down in grits because it's pretty quick to find the surface with the next grit. They are generally within a few thousandths of each other. Stepping down from a 220 Norzon to a 400 grit J-flex is about .0.025" so the difference is significant. Splitting the belts is easy with the belt splitter except the Trizact belts. The structured abrasive causes problems when cutting the belts and it's hard to clean up the edge after splitting. That said, the finish left by a Trizact A45 is significantly better than that of a 400 grit J-flex.

I also think my contact wheel is too soft. It is my understanding that there is going to be some ramping on the edges of the steel regardless of how hard the rubber contact surface is but, I think a harder wheel would reduce the effect. I am probably going to order a new wheel sometime in the future and I'm thinking it will be somewhere near 100 duro. It will also probably be 2" wide. I like that I can get across the material faster with the 1" wheel but I want to run the Trizact belts and the splitting is a pain. I looked into 1x72 belts and they only make the A45 in that size.

One last note on the construction and design of my arm; the handle doesn't really work for pulling tension off the belt. It puts too much side load in the tube and jams. If I were to do this again, I would design the upper spring perch to have a swell in it that I could grasp and pull down which is how I'm doing it now. Other than these fairly minor issues, this thing is awesome and I find it much more useful with the belt conversion.

Bob
 
Wow, give you a piece of steel and get a whole belt sander back.

I am impressed.

Larry
Tinkerer
 
Ok, been a while since I finished this conversion. I have found another great reason to do the belt conversion on surface grinders. Thicknessing G10!

Untitled by Ranger_Bob, on Flickr

I am working on my second folder and yesterday I decided that my spacer would be G10 to match my scales. I tested it out and it worked great so, today I brought my 3/16" peel-ply G10 scales down to 1/8". The scales are attached to 1/8" steel parallels with high quality carpet tape (basically 2-sided duct tape). I was using a 60 grit Blaze and taking a .010" cut with .300" stepover. They never loosened or lifted and I had no trouble getting .001" accuracy while removing .063" total.

Bob
 
Ranger- Im sure you have figured it out but most belt surface grinders use a 90 durometer wheel
 
Thanks for sharing this WIP, so cool being able to follow along and wow it turned out great! This might be a dumb question but does the surface grinder hold your work piece in place by vacuum force or is it magnetic?
 
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