disc sander design

scott.livesey

scott.livesey

Dealer - Purveyor
Hi,
I have been looking at the 9" disc that will mount on a 5/8 shaft. I have a phase inverter and vfd so I can go as fast or as slow as I need. my idea is to mount vertically with the disc inside a 10" or 12" deep dish pizza pan( commercial pans are pretty strong and have a 3" side) that has a cut down area so you can move the blade in and out. blade will be mounted on a jig so angle to disc is exact. to start, I was going to use waterproof silicon carbide paper with either a drip or squirt bottle.
the pizza pan is what i come up with for something to enclose the disc. sealed flanged bearing on disc side of the pan. plastic or wood to cover the half of the disc not being used.
Here is where I need help. hi speed or lo speed. My thought is 200 to 300 rpm on wet 3000 grit paper should give close to a mirror finish. there are also felt pads available so I could use abrasive compounds as fine as they make. I would not be starting with 3000 grit, the usual 240,320,400,600,1k,1500,2k. Am I on the right track or do I need to get my medications adjusted again?
scott
 
Not sure why you want to use a pizza pan. To keep dust out of the motor? You should be using a TEFC motor and dust won't be a factor. I think the pizza pan will just get in your way. Use an air hose to clear off the shaft and motor every once in a while and you will be just fine.
 
barry:
I want to use the disc sander wet and want to keep the water in one place not all over my bench and floor.
the other part is safety, you only have a small window where you can actually see and touch the disc.
Is my idea on speed in the right direction?
scott
 
scott.livesey said:
barry:
I want to use the disc sander wet and want to keep the water in one place not all over my bench and floor.
the other part is safety, you only have a small window where you can actually see and touch the disc.
Is my idea on speed in the right direction?
scott
Click to expand...

Scott,
BAD IDEA!
If you are using water? You want a TEFC motor or you could electrocute yourself!

Laurence

www.rhinoknives.com
 
I dont like it. The pan may help you control some of the water, but not all of it. I refer you to Laurance's post. I cant help but think the pan is going to interfere with your efforts to adress the disk at grinding or polishing angles.
 
i have a tefc motor i am going to use. i want to make it where i can work wet if i choose. Is a motor speed of 200 to 400 rpm the right direction. i am planning on using this for final sanding of the blade. my thinking is that it would be more controllable at a low speed. again, is my thinking in the right direction or do i need new meds?
scott
 
Slow is better for the finer grits. You will probably not like those swirls as a finish and it will be extremely hard to get them even if you do like it. I will use a 220 going fairly slow to flatten the blade after heat treating and before hand sanding. The disc is vertical but the motor horizontal and I address it and hold the blade like I am on the belt sander. You should be able to use a little water, oil or other lubricating liquid just don't get crazy or you will be wearing it. I do use wet/dry paper but always dry. It seems like you are trying to speed up the finishing process by going up to 3000 grit paper on the disc. I'm not sure it is going to work as well as you think. Once you get the blade dead nuts flat and all the deep scratches out hand sanding goes pretty quick. One thing I have just started using on the finer grits is a tapping fluid it is dense and makes a great slurry to suspend the metal particles plus the paper seems to last just a bit longer.
 
I use my disc with wet/dry "Black Beauty" paper, when finishing, finer grits create much more friction. As I dip the blade, if not careful I load the paper up VERY quickly with slurry from the process.
I use my disc on almost every knife I use. Love the ability to machine grind on a large flat at very low speeds. I usually go up to 800 grit, then start hand sanding at 600, just takes a few minutes to finish!

God Bless
Mike
 
Cool that you have a TEFC motor. I don't think you are going to be able to go finer than about 220 - 400 Grit on a disk. Your idea of up to 3000 G will show the adhesive and any other material on the disk.

You do have the right idea about going slow with the finer grits. After about 600 grit its hand sanding in my experience.

Laurence

www.rhinoknives.com
 
BarryC said:
...One thing I have just started using on the finer grits is a tapping fluid it is dense and makes a great slurry to suspend the metal particles plus the paper seems to last just a bit longer.
Click to expand...

I used tapping oil for quite some time for the same reason. I switched over to synthetic oil and have no regrets. I use Royal Purple 5W-30 high performance synthetic oil for it's particle suspension atributes and could not be happier. Besides, in most cases it is much cheaper than the tapping oil I was using.
I am reasonably sure that there are cheaper synthetics that would work as well, but I really dont use much per blade so it lasts me a long time.
I bought a small empty dropper bottle from my local hardware store to use as an "on the bench" dispenser when I was using tapping oil. I have since switched to a small used Dawn dish soap bottle because I like the non drip caps they put on them.

It may well be a pipe dream for me. A kind of a ..."I want it will work better therefore it has to"...situation so to speak.
But consider the aim of the manufacturers for the intended use of each of these oils and I think the synthetic is better suited to the task.

Just thought I would throw that out there....
 
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