Radial arm saw grinder conversion

[Ferrous Turner]

There seemed to be a little interest in this conversion, and I didn't want to hijack Danny's thread, so I'll post a few pictures here.
A little back story... This all started when I built an anvil. I didn't really need an anvil, but I'd been watching some YouTubes on building anvils and you know how it goes.
Anyway, the top is mild steel and produces a thud (and a dent) when hit with a hammer. I figured I needed something a little harder on top. Not knowing anything about tool steel, I found a good deal on a piece of 1/2" X 3" D2 bar stock. It was only then I started educating myself on hardening, tempering and what it takes to "finish" a piece of tool steel. Naturally I had to built a hardening oven for this (which is a thread in itself).
So, now I have this oven for one piece of steel. What else can I do with it? Why, knives need to be hardened, why not try that! Looked into knife making and noticed everyone was using a 2 x 72 grinder. Oh gosh, I just might have to build one of those too.
I'd just picked up a load of scrap steel (you can never have enough), and started using what I had.
I bought the platen assembly from Oregon blade maker. I figured; why reinvent the wheel. For $100.00 you can't beat it. For the drive roller I first used a 3-1/2"steel conduit coupler (OD 4"). I machined and attach the two 1/4" discs, in the picture, which made a rabbet joint around the edge.
This one turned out to have some vibration, either from being unbalanced or poorly machined (most likely).

I just cut off a piece of 3" pipe for the next one. I happened to have a few 3.5" steel discs which fit perfectly on the end. This one went a lot better without a rabbet joint (unnecessary). I spot welded it on the inside to connect the two and then drilled the 5/8" hole on the lathe.

I sandwiched some large 1/2" bar stock between a couple of pieces of beefy angle iron to complete the frame. I also bolted a couple of pieces of smaller bar stock to the saw stand to provide a base.

I then built a tracking arm and roller. I used a piece of 2" acrylic solid rod as the roller material. I machined a couple of 1/2" bearings into the ends and attached it with a bolt. I still couldn't get the belt to stay in one place, it kept wandering back and forth. So I put a piece of electrical tape around the center of the tracking roller and some on the drive roller. This helped a lot, but I'm going to try crowning those two rollers to get better tracking.

The belt speed is still a bit slow, so I got a coupling for some 4" pipe (4-3/4" OD) which I still need to assemble and machine for a larger drive roller. I've been eyeballing some VFDs on Ebay, but the recent projects have stretched the budget a bit, and the wife is not real happy about it. Since I'm just grinding steel, the bigger roller should be fine.
A nice feature of this grinder is being able to tighten and loosen the belt by sliding the motor back and forth on the rail. It has a screw lock to tighten it in place. It also has the on / off button right where you need it (don't have to build a control box).
Not the finest belt grinder, but then it only cost me about $150.00 to build.

Cheers,

Ted

 

[MAKEITOUTOFWOOD]

Very interesting use of the old radial arm saw. Thanks for sharing.

 

[Ferrous Turner]

I attempted to build a larger drive roller today. Took me most of the day at the lathe to try and get everything square and straight. I was using the 4 jaw chuck, and indicating the piece, but I still managed to screw it up. The hole turned out to be 5 thou off center, so I built a little jig to hold it in the 3 jaw chuck.

This is a piece of 2" round stock I bored out to 5/8" and faced to hold the roller square to the lathe as well as on center. I have a 5/8" bolt holding everything together.
I re-turned the roller and it looked great in the lathe. Unfortunately, the motor still considered it unbalanced (and it was). I indicated it on the motor shaft, and sure enough it was still off center. WTF???
The culprit turned out to be the piece of 2" round stock (which I hadn't checked for roundness). So, I'm turning a new piece which is hopefully accurate and I'll try turning the roller again. I just hope I get it all figured out before I run out of metal on the roller.
Here's the new one compared to the smaller one I had:

 

[Ferrous Turner]

I had no luck getting the larger roller to run true. I felt I was chasing my tail while trying different ways to get the outer surface true to the hole. I eventually took too much metal off of one side and had to give up on that roller. It was a lost cause from the beginning when I drilled the hole off center.
Anyway, I turned a piece of 3/4" acrylic sheet to approx 5" od to see if I could get anything to run smooth on that motor. Sure enough I got some vibration and began to smell a fish.
Here was my setup for turning the disc:

I cut the head of a 5/8" bolt and made sure I had the acrylic riding on the shank and not on the threads.

I even stuck the live center on it for added precision, then turned it smooth.
At this point I began to suspect something was not right with the motor shaft, so I stuck an indicator on it.

Sure enough, I had 2 thousands eccentric. Just enough to start a vibration. This motor will never turn a large roller without vibrating.
So, I could either remount this motor with a pulley, or get a whole new motor. I do have a big old exercise machine that we're not using which I may cannibalize for the motor and controller.
Sigh... I had high hopes...

Ted

 

[Ferrous Turner]

On another thought, if it's just a bent shaft, I may be able to persuade it back to true with the proper cheater bar and hammer.

 

[danny12]

Good Wright up and definitely thinking out of the box.
I like it.

 

[middle.road]

cool idea!
When you had the 5/8" threaded stud in the chuck did you happen to check it's runout?
I'm thinking that if there's a couple of thou runout on the 3-Jaw then you'd end up with .005-.006 runout on the saw.

 

[Ferrous Turner]

cool idea!
When you had the 5/8" threaded stud in the chuck did you happen to check it's runout?
I'm thinking that if there's a couple of thou runout on the 3-Jaw then you'd end up with .005-.006 runout on the saw.

I checked it and it was good. I'm going to try and straighten the motor shaft If I can. It's a brass shaft and probably bends fairly easily. I'll have to protect the threads, so I'll probably make an acrylic sleeve to fit over the threads and into a pipe. If I can find a good straight pipe, the angle of offset should be pretty obvious as I rotate the shaft.

 

[Ferrous Turner]

Wellll... I tried to straighten the shaft. In doing so I removed a plate from the front of the motor, thinking that I could pull the front cover off and check the bearing. Apparently this plate held something on the other side of the cover (probably something to do with the auto braking system), and I can't get the cover off to realign and attach it. The armature rotates freely, but the motor won't start (hums like the rotor is locked). I think the front cover is attached to the front bearing which is pressed in. It's attached to something I can't get to anyway. There's nothing to attach a puller to either.
Time for plan B. I ordered a new motor and I'm reverting to a more conventional approach. I'll probably take the whole arm assembly off and just use the stand as a sanding center.

 

[Ferrous Turner]

I made a little progress on plan B. I got a 2hp motor and fabricated some mounting rails for it. I bought a 3/4" rod for the axle since I already had a couple of pillow bearings that size. I also got a couple of pulleys to connect the motor and the axle. This will be my first attempt to mill key slots in the axle.
Here is the general arrangement of motor and pulley. I was pleasantly surprised that the motor turned in the proper direction on first startup, although it says in the instructions that you can change the direction of rotation by swapping a couple of wires.

I installed a basic power switch, which turned into a job that took about three times as long as it should have. I made the box out of a piece of square tubing, and all the little bits of machining and welding seemed to stretch on all morning. Electrical's done anyway.

I mounted the belt adjustment arm on a drawer slide. I'm going to try and rig up a threaded rod and a handle to raise and lower it. The slide is pretty rigid front to back, but it has a little slop side to side. I may install a hold down bearing to keep it from flexing.

Ted