# I need an idea



## Janderso (Jan 31, 2020)

I have the parts to build my slow speed diamond disc lapping machine.
I’m planning on making the box out of the aluminum sheet the components are resting on.
I love the idea of magnets and a pilot hole for the 6” discs.
The motor has these really handy built in 4 square mounting holes that I would like to mount directly to the aluminum plate.
I have a 6” aluminum disc as shown.
I really want a runout free rotation.
The table will pivot positive and negative angles, I got that.
	

		
			
		

		
	





I embrace your ideas.
Thank you, I won’t let you down.
Jeff


----------



## Ulma Doctor (Jan 31, 2020)

broach a piece of stock and turn between centers to create a long bushing
leave one end with a substantial step and turn a large washer for support of the back side.
thread one end of the bushing and use another smaller washer and a retention nut to lock it all down
concentricity will also be determined by the center bore of the diamond disc, if that is off the disc will wobble radially


----------



## mikey (Feb 1, 2020)

Two thoughts came to mind. First is that I hope your gear motor has good bearings and not bushings. The plates take a lot of force when you sharpen stuff on it, especially at the edges, and this will stress those bearings. Second, water resistance. When grinding stuff on a diamond wheel, it helps to use a wetting agent to help the wheel cut more efficiently. You have to keep the fluid and the grinding particles that go along with it from migrating into your bearings.

I have an Accu-finish and it has a pulley/belt system to keep fluid away from the motor - good idea, I think.


----------



## Cooter Brown (Feb 1, 2020)

I would make a few parts like kinda this...... and tap the end of the motor shaft if it doesn't aleady have threads.....


----------



## Latinrascalrg1 (Feb 1, 2020)

I agree with Mikey in that I think a seperate pulley connected to the motor with a belt would be your best setup option.


----------



## Nutfarmer (Feb 1, 2020)

You are over think this. As long as the disc are turned at the proper rmp all is good . Build it. It will work just fine.


----------



## Cooter Brown (Feb 1, 2020)

This guy is right.

You are not trying to market this, the motor has a TEFC case, just attach the wheel right to the motor like a bench grinder.....


----------



## extropic (Feb 1, 2020)

If that gearmotor/controller combination will give you the RPM that you want, put the disc on the gearmotor. If you might need to change the disc RPM (outside of the gearmotor RPM range) use a pulley system.
To protect the front bearing, I would put a felt washer (OD as big as the boss on the gear housing), oil soaked, captured between the gear housing and disc hub. Oil it once in a while and it will keep water and grit out of the bearing without much drag.

Looking forward to following the build. Nice project.


----------



## savarin (Feb 1, 2020)

I used to facet gemstones but havnt for around 10 years.
I was seriously considering converting my facet machine into a carbide sharpener because the angles can be set for anything.
As it stands it would be best on solid round carbide bits but with a bit of thinking I believe it could hold inserts and other sizes.
The big problem is I am way too busy with house modeling and moving to even start anything like this.
It may be worth looking at a facet machine for design ideas and those diamond disks look seriously like the ones I used to use, from180 grit up to 1200 grit.


----------



## Janderso (Feb 1, 2020)

I knew I could count on you guys.
Thanks for the good ideas, I appreciate it.
I’m hanging an interior barn door today, maybe I can get started after that is finished.
Got to keep Glenda happy.


----------



## f350ca (Feb 1, 2020)

Think you'll need a hub to mount the aluminum disk. Face the back side of the disk and a suitable sized piece of material for the hub. Bolt them together with counter sunk heads in the disk, locktite the screws. Then face the front, form a register for the hole in the disk and bore the hub in one operation to reduce runout. 
I had sufficient 4 inch stock to make the hub and plate in one piece but did the last operations in one setup and can't feel any runout when using it
I wouldn't bother with the keyway, set screws at 90 degrees will turn it, the diamond disks don't take a lot of power.
You will need dowel pins to drive the disk as Stephan did in his video. Do as he did and drill the disks when your set up to drill the holes in the plate. 
I ordered more disks for mine now have to make a setup to drill them.
I used 3/8th rare earth magnets I had for cabinet door latches. Drilled the disk with an end mill and epoxied them in. Works great, clamp them down while the epoxy cures, mine came up out of the hole and had to be ground down flush.
A shaft on bearings would be best but this isn't going to see industrial use, the gear box should carry the load fine. If not redesign at that point. 
I used a shaft and belt drive, only because I couldn't find a proper speed gear motor. Ran mine at 500 rpm, only had slower motors around.




Greg


----------



## Winegrower (Feb 1, 2020)

Off topic maybe, but just for concepts and ideas, here is a mechanism I made to polish glass rods at a very actue angle.   My drill press was the disk motor and a cheap motor and gear train provided the linear motion.
View attachment 9B5838EF-43F9-42DB-8C6E-246A21854A4A.MOV


----------



## middle.road (Feb 1, 2020)

What were the specs on the motor and controller? And for the finance dept. - how much were they?


----------



## Winegrower (Feb 1, 2020)

If that's for winegrower, the motors integrated with the gear train were eBay specials, no real specs except 12VDC motor, variable speed with voltage.   At 12 volts they were about 100RPM as I recall.   Maybe $15 each, I bought 3.   "Controller" so to speak was an HP lab DC supply.


----------



## Janderso (Feb 1, 2020)

F350, I like your plan dood.
Hung the door. Looks good.


----------



## Janderso (Feb 1, 2020)

Made some progress today.
I had to stop when I spent half an hour looking for a suitable tool and tool path to cut the 4mm key way.
I have a full Imperial broach set but I have virtually no metric tooling.
I need to ponder this one.
A few shots of my progress. I plan on milling a flat, drilling and tapping for a set screw. The fit is good, I pulled it off.
I also plan on cutting a register to center the diamond plate, magnets and drilling and tapping the motor shaft.
Right now the aluminum backing plate runs smooth as glass.
I’m thinking of using super glue to a sacrificial stock to turn the od.


----------



## Janderso (Feb 2, 2020)

Mikey mentioned earnings vs. bushings, hmm, I’m not sure which this has. 
Cooter brown, I like your idea, my hub is kind of like your design.
F350ca, the magnets and the center nub the disc centers on is a great idea. You used pins, I was thinking set screws but pins would work with the beveled screw holding the wheel into the shaft.
Im trying to avoid grit and water entry through the disc, if I use the method just mentioned I can’t see anything getting back there?
I was going to use a sewing machine motor and pulley but then I found this 125 rpm geared motor and controller for less than $35.
Heck, the sewing machine motor and HF controller was less than $50.
Im going to over think this some more. It will work, whatever I come up with.
Im having fun and learning as I go along


----------

