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Disc sanders?
- Thread starter bryce
- Start date
- Joined
- Nov 25, 2000
- Messages
- 5,548
JMO, but I believe a 1 HP motor is quite sufficient, although the RPM is way high on yours.
I use a couple of 1 horse motors running 1750 RPM. I want to replace them with variable speed motors in the near future so I can slow them way down when I wish to.
I believe the 21/2HP to be overkill, but what the heck, if you already have it, you might as well use it, as long as you have 220V available.
The one problem I see, is getting a 9" disc with the arbor size to fit the shaft of the bigger motor. Most discs are made with 1/2"-5/8" arbor holes. A 21/2HP motor could have up to a 11/2" shaft.
You could be lucky and find that it's 5/8" though.
I use a couple of 1 horse motors running 1750 RPM. I want to replace them with variable speed motors in the near future so I can slow them way down when I wish to.
I believe the 21/2HP to be overkill, but what the heck, if you already have it, you might as well use it, as long as you have 220V available.
The one problem I see, is getting a 9" disc with the arbor size to fit the shaft of the bigger motor. Most discs are made with 1/2"-5/8" arbor holes. A 21/2HP motor could have up to a 11/2" shaft.
You could be lucky and find that it's 5/8" though.
- Joined
- Jan 24, 2003
- Messages
- 2,767
Gonna stick my neck out here. I'd use the big motor for a 12 to 18" and the 1 HP for a 9" to 12". Both have more than enough power for those sizes. I have a 12" I made, and the motor has less than 1 HP, but it will do the job. A big disc grinder I have used, probably about a 24" or so, has a huge 3 phase motor. What I noticed was as you start getting above 16" or so, the HP requirements ratio seems to increase. Those larger disc grinders have pretty heavy, thick discs, also.
Sorry guys I ment I have (2) 3/4 horse motors however I have a 14 horse sitting around...... anyways will a 3/4 horse at 1750 be enough?
and who sells the disc's I know rob frink does but does anyone else or are the disc's he sell by far the best? I am on a budget though
and who sells the disc's I know rob frink does but does anyone else or are the disc's he sell by far the best? I am on a budget though
- Joined
- Nov 27, 1999
- Messages
- 3,745
The 3/4 will be OK for the 9" Bryce but I wouldn't go any larger. If you are really worried about cost, make your own disc. I have several that I use that I made. I'm thinking about making one from steel so I can use magnetic sheets with different grits for quick changes.
- Joined
- Jul 8, 2001
- Messages
- 849
I have a disk grinder that I got from Tru Grit and it has a 9" disk with a 1/3HP motor turning 1150RPM and it is just right with plenty of power. Gib
- Joined
- Nov 25, 2000
- Messages
- 5,548
3/4 HP will work just fine.
A 9" disc gives you the advantage of using 9"X 11" sanding sheets. You spray the disc with 3M feathering disc adhesive, let it set up for a few minutes, per instructions, and slap a sheet on. just trim off the excess with a junk knife.
It's the difference between .50 each, and 2-3 dollars each. If you do the adhesive right, you can get several changes out of one application, before having to clean the disc and reapplying.
You can get the adhesive from K&G, or any bodyshop supply paint store.
http://www.knifeandgun.com/catalog/adhesive_186655_products.htm
BTW, you can get some discs fairly cheaply from Grizzly. get the 9" replacement discs for the 6"X48" sander.
A 9" disc gives you the advantage of using 9"X 11" sanding sheets. You spray the disc with 3M feathering disc adhesive, let it set up for a few minutes, per instructions, and slap a sheet on. just trim off the excess with a junk knife.
It's the difference between .50 each, and 2-3 dollars each. If you do the adhesive right, you can get several changes out of one application, before having to clean the disc and reapplying.
You can get the adhesive from K&G, or any bodyshop supply paint store.
http://www.knifeandgun.com/catalog/adhesive_186655_products.htm
BTW, you can get some discs fairly cheaply from Grizzly. get the 9" replacement discs for the 6"X48" sander.
FWIW,
I have a variable speed, DC, treadmill motor for my KMG. It is double shafted. On the other end I have a disk. That gives me a variable speed, bi-directional, 2hp disk grinder for just the price of the disk. Actually I had an 8" available and plan on buying a nice 9" Frink disk one of these days.
Just an idea.
Steve
[edit] BTW bi-directional is really, really handy. If one of your motors is reversable I'd add the switch.
I have a variable speed, DC, treadmill motor for my KMG. It is double shafted. On the other end I have a disk. That gives me a variable speed, bi-directional, 2hp disk grinder for just the price of the disk. Actually I had an 8" available and plan on buying a nice 9" Frink disk one of these days.
Just an idea.
Steve
[edit] BTW bi-directional is really, really handy. If one of your motors is reversable I'd add the switch.
Bryce
Someone had mentioned buying replacement disks from Craftsman and others for about $20 and mounting them on your own motor. It was in a similar thread that I had started a few weeks ago. I've not had time to follow up on it yet.
Peter
You mentioned building your own disk. Can you provide some details regarding how you did that and what material and equipment you used? Are they comparable to the disks that one would buy from Craftsman? Also, where did you get the magnetic sheets?
Thanks.
Phil
Someone had mentioned buying replacement disks from Craftsman and others for about $20 and mounting them on your own motor. It was in a similar thread that I had started a few weeks ago. I've not had time to follow up on it yet.
Peter
You mentioned building your own disk. Can you provide some details regarding how you did that and what material and equipment you used? Are they comparable to the disks that one would buy from Craftsman? Also, where did you get the magnetic sheets?
Thanks.
Phil
- Joined
- Nov 27, 1999
- Messages
- 3,745
The disc itself isn't all that hard. You could drill and chuck a 9X9" sheet of 1/4 plate in your lathe, but since a lot of people don't have a lathe, here's another way.
Drill a hole on the center of a plate. take a 1X12" pine board about 14" long and drill it for a pin the same size as the hole in the plate. Put the plate on the stud.
Replace the blade in your table saw with a metal cutting blade.
Adjust the fence so the blade is touching the side of the plate.
Back the board up and turn the plate so the Blade will cut a corner off. Cut it off and do another corner and so on.
When the thing looks round you should be able to spin it next to the blade with very little contact.
Countersink the hole in the plate and mount a flat head screw with a rod coupling on the bottom. You don't need much screw inside the coupling. Weld or solder the coupling to the plate and drill it to the shaft size of the motor. Drill and tap the side of the coupling for a set screw and file a flat shim to go on the shaft flat.
Mount it and use a file to dress the edges.
I have not used the magnetic sheets yet. I read an article about one knifemaker who was using them and he just used Ben Franklin sheets. The grinder will have to be pretty slow or I expect you will get some UFO"s
Drill a hole on the center of a plate. take a 1X12" pine board about 14" long and drill it for a pin the same size as the hole in the plate. Put the plate on the stud.
Replace the blade in your table saw with a metal cutting blade.
Adjust the fence so the blade is touching the side of the plate.
Back the board up and turn the plate so the Blade will cut a corner off. Cut it off and do another corner and so on.
When the thing looks round you should be able to spin it next to the blade with very little contact.
Countersink the hole in the plate and mount a flat head screw with a rod coupling on the bottom. You don't need much screw inside the coupling. Weld or solder the coupling to the plate and drill it to the shaft size of the motor. Drill and tap the side of the coupling for a set screw and file a flat shim to go on the shaft flat.
Mount it and use a file to dress the edges.
I have not used the magnetic sheets yet. I read an article about one knifemaker who was using them and he just used Ben Franklin sheets. The grinder will have to be pretty slow or I expect you will get some UFO"s
