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View Full Version : I need some disc sander advice.



DICKEYBIRD
11-13-2007, 10:49 PM
I've been wanting a bigger disc sander (only have a little hobby 4" one now) in my shop and have now accumulated enough good junk to start putting one together. I have enough 1/2" aluminum plate and larger chunks to make a very solid mount/base, adjustable table and disc & hub. I came across an old (50's - 60's?) Westinghouse 110v 1/4 hp 1725 rpm motor today for free. It says "Type FHT AC Motor 56Z Frame" on the name plate and when I cobbled up a patch cord and plugged it in it sounds smooth as silk and feels plenty powerful.

Anybody have any advice as to what diameter I should make the disc? I want to run it direct drive and would like to choose a size that uses a commonly available (translation: cheap) disc that wouldn't bog down the 1/4 hp motor.

I'm also curious about zirconium oxide discs. Anybody got a line on a good supplier and do they really last a lot longer?

What say you'uns?

wierdscience
11-13-2007, 11:14 PM
I have a 12" disc sander that's direct drive(no belt losses)that runs a 3600rpm 1hp motor and the power is borderline not enough.

If it were me I would go no less than 1hp and no less than a 12" disc.Direct drive is also nice since you don't need any pulleys etc and they run much smoother as a result.

I also bought a 12" Grizz disc sander for a whopping $140+shipping that's darn hard to beat.

Yes the Zirconia discs last a long time,6 maybe 7xs what AOX does.I just by mine from McMaster Carr,$4.25/disc for US made heavy cloth backed discs with good glue.

dalee100
11-14-2007, 08:23 AM
Hi,

I'll second Wierdscience, 1hp is barely enough on a 12" disc. I can trip out the heaters on mine. That 1/4hp isn't much better than what you already have.

dalee

Barlow L
11-14-2007, 08:48 AM
I am kicking around the idea of building my own disc sander as well. I want something in the 16"-20" range. Is there a formula for calculating horsepower to disc size?

Also, whats the best choice of material for the disc, aluminum or steel. What about disc thickness?

I hope you don't mind me stepping in your thread Dickeybird with questions of my own.

Lee

DICKEYBIRD
11-14-2007, 09:27 AM
Thanks for the input guys and no sweat Lee on the big sander question. I'm curious if there's a rule of thumb calc for hp/disc size as well.

I don't have the extra $$ to just go out & buy one right now but I do have the stuff gathered up to build one for nuttin'. I suspect that old American iron 1/4 hp motor has way more than 1/4 the power of a modern Grizzly (Chinese) 1 horsepower motor. My Chinese 4x6 bandsaw has a "1 hp" motor on it and it won't pull the skin off a rice puddin'.;)

I grabbed the pulley with a rag, plugged it in and tried to stop it by hand and let's just say it feels pretty stout. I'm guessing an 8" disc would be pretty close; maybe even 9" or 10". I'm thinking the slower (1750) rpm motor will need a fairly large disc to work properly. I guess it's all just a crapshoot 'til the metal hits the wheel and the sparks start a'flyin!:)

ammcoman2
11-14-2007, 10:10 AM
A few years ago I bought one of those combo 4"x36" belt/9" disc sanders at a sale. The motor was clearly "underscoped" and operating the thing always p*ss*d me off.

I finally ripped off the the belt part and now it works very well as a disc- alone sander. Can't tell what HP the motor is but now it takes a determined effort to slow it down.

I also have a 1"x42" belt sander with a 1/4 HP motor that I installed. It needs to be handled carefully to prevent stalling so I would echo what others have said regarding more power. On the other hand those old motors were very conservatively rated so you may be ok.

Regards,

Geoff

Bill Pace
11-14-2007, 10:24 AM
Dickybird, --- I've got an 8" disk off a deceased 1x42 - 8" belt/disk sander that expired rattling around here that youre welcome to, it'll ship on USPS for cheap ---- IIRC it has a 5/8" hole

And, I think youre right about that old motor, I bet it'll handle an 8" easy ----the Chinee motor that was on that sander was 'rated' at 3/4hp but it was pretty wimpy.

Several yrs ago the company that makes those "3 in 1" sorta woodworking machines (Shopmate??) offered a 12" disk to adapt to the motor on it for $25-30 and I built a sander up off a 1hp scrapyard motor .... that thing has got to be one of the more handy tools in the shop! Course this was long before HF offered their 12"er for $99!, I probably spent that much on making that one up.

Anyway, if you want that disk, DickyB,--- send me a PM

Ries
11-14-2007, 10:38 AM
Your expectations may be different than mine- but I have a horse and a half on my 12", and would never go for a smaller motor.

Of course, I also dont use cheap sandpaper- only Klingspor CS411, which is a blue zirconia alumina paper. Its false economy to buy cheap paper, in my opinion- you just tear thru it. A good zirconia, from Norton or Klingspor, will last you months of sanding stainless. We can take a piece of 3/8" round stainless, and feed it into the disc til there is nothing left but your glove smoking.

As for bigger ones- for 16" to 20", the cheap imports start at 2hp, the decent domestics usually run from 3 hp, up thru 5hp for the beefy ones, to a rare 7 1/2hp model or two.

More power is good.

Alistair Hosie
11-14-2007, 10:41 AM
I have several three phase 16" and several 12" machines the big ones are best.Alistair

DICKEYBIRD
11-14-2007, 10:54 AM
Thanks Bill, PM sent!

GrahamC
11-14-2007, 10:43 PM
Hey Milton,

I made a disc sander a while back primarily for use with wood but lately has been getting used for metal work too.

I started with a 9" replacement disc for a Sears disc sander - ordered it from their parts department and cost all of $15. I could have made one but for the time and trouble it wasn't worth it. Motor is an old GE 1/2 HP with a 5/8" shaft and the remainder being made of plywood and pine. It has three feet so it sits flat - I used Hocky pucks for the feet (bore a small socket with a Forstener bit and screw on to the wood frame) cheap, solid and works.

http://www.aei.ca/~planophore/discsander_001.jpg

cheers, Graham

wierdscience
11-14-2007, 10:56 PM
Thanks for the input guys and no sweat Lee on the big sander question. I'm curious if there's a rule of thumb calc for hp/disc size as well.

I don't have the extra $$ to just go out & buy one right now but I do have the stuff gathered up to build one for nuttin'. I suspect that old American iron 1/4 hp motor has way more than 1/4 the power of a modern Grizzly (Chinese) 1 horsepower motor. My Chinese 4x6 bandsaw has a "1 hp" motor on it and it won't pull the skin off a rice puddin'.;)

I grabbed the pulley with a rag, plugged it in and tried to stop it by hand and let's just say it feels pretty stout. I'm guessing an 8" disc would be pretty close; maybe even 9" or 10". I'm thinking the slower (1750) rpm motor will need a fairly large disc to work properly. I guess it's all just a crapshoot 'til the metal hits the wheel and the sparks start a'flyin!:)

Unless that motor was built in the steam era it's nothing special.The 12"Grizz sander I have is a sure enough 1hp,I can radius the end of a 2x4 in seconds,that's a full radius 1-3/4r.The other sander is 1hp3~ and "old arn",it's still close to being weak.

Not arguing,just saying that in this case more IS better.

jacampb2
11-15-2007, 12:41 AM
I was all geared up to build a disc sander in the neighborhood of 16-20"s with an old tablesaw I had kicking around the shop. I saw the price of media for a 20" sander though, and that kind of turned me off. I run a little 6" disc/belt sander right now that I use only as a disc sander and zirconia alumina discs are about $1 a piece. I am still going to build something bigger, but no where near the original plan. Maybe a 12" one, I intend to run a 3hp motor on mine. My little one has a 2/3 HP motor, and it is built into the base of the sander. I had to take it apart, because I couldn't believe a 2/3hp motor could fit in there. The motor is a odd frame, but it is a pretty big devil for going into the base.

I have never had trouble with that motor and the 6" disc, however I have an identical sander that I lengthened to take a 4x54" belt and use that for belt sanding only, the motor is seriously under sized for that application.

Later,
Jason

sasquatch
11-15-2007, 08:06 PM
I agree a 1H.P. is a minimum, a 1/4 H.P. would be pretty Wimpy, and Very Slow!!

Ray in N. Ont.

Barlow L
11-15-2007, 11:52 PM
What thickness are the larger 16-20" disk?
Whats the ideal material; steel or aluminum?

Lee

wierdscience
11-16-2007, 09:21 AM
What thickness are the larger 16-20" disk?
Whats the ideal material; steel or aluminum?

Lee

I've seen both aluminum and cast iron,but not steel,I think it might want to ring.Last big sander I used was a 22"Oliver and the disc on it was about 5/8" near the rim and looked like it had a slight,maybe 5* taper on the back.I've got a 20" sander I started building nearly 3 years ago and I'm using 3/4" aluminum on it,maybe I'll get time to finish it this year:(

BobWarfield
11-16-2007, 12:43 PM
We had a 20" Chinese import at the school shop where I learned to weld. That thing was great. Tons of horsepower, I think it was 3HP or so. It was the tool I coveted most from the shop after the Big Miller Mig welder they had.

I keep thinking I'd like to build a combo disc/belt sander to use for knife making someday soon. If you look into the book $50 Knife Shop by Wayne Goddard, he has some decent plans for a disc/belt sander in there. It's an entertaining book and worth a look see.

Cheers,

BW

kc5ezc
11-16-2007, 09:17 PM
I have a 30" disk sander with a 5 HP 3 phase motor for push.
Gets the job done. Also has a recipricating sander on the other end with a 1.5 HP motor. I mention these numbers to give you some idea of power required. This is a piece of 'old american iron'. If I could figure out how to move it I would sell it. Liked to of killed me getting it into the shop several years ago. Precut ALOX sandpaper for the 30" wheel is about $10 a sheet in a heavy weight back.

George Barnes
11-16-2007, 11:39 PM
Here is one that I made quite a few years ago and it sees daily service in my shop. This is a 12" unit that is powered by a 3/4 h.p. 1725 motor. I don't have any trouble as far as having enough power, but then I'm not trying to grind stuff into oblivion. The table does not tilt on this one, but I have made the little adjustable fence for doing known angles like 22-1/2, 30, and 45 as well as 90. There is a pin in the bottom of the fence that engages the holes in the table for the preset angles. The fence can be turned over and any other angle can be accomplished by clamping the fence to the table.

I have a reversing switch on the motor so that gives greater access to grinding parts. Notice the second set of fence holes also for this feature.

http://img.photobucket.com/albums/v707/gbarnes/DiscSander.jpg

The disc is 5/16" aluminum plate and the hub (not shown) is aluminum that mounts directly to the motor shaft. The table is 3/8" steel plate and the motor mount is 10 ga. sheet the has been broke in 4 - 45 bends. The side plates are flame cut 7 ga. sheet with the table mounts being 3/8" x 1" bar stock.

http://img.photobucket.com/albums/v707/gbarnes/DiscSanderParts.jpg

The two extra holes on each side of the table are for set screws to adjust the table to perfectly square to the disc in case you miss a little in getting everything perfect when putting it together.

DICKEYBIRD
11-17-2007, 08:15 AM
Thanks for the great pictures George & Graham. Good, solid engineering on both. I hope mine comes out half as nice as yours!

Being lazy, I couldn't justify all the work needed to make a tilting table either. For my shop use, I can't forsee many special setups that would require tilting the table. I plan to mill a slot in the table and use the miter attachment I made for my grinding rest for any angle cuts. Most of my stuff just needs a lttle freehand work anyway.

As far as the disc size/hp issue, I'm going to go with what I have at hand right now without spending anything: The big ol' antique 1/4 hp motor and the 8" disc I now have thanks to the generosity of Bill Pace.:) I 'spect 8" might be a tad big for heavy hoggin' but I'll betcha it'll do more work than this little feller. It's a H/F I got on sale and hacked in a light dimmer/speed control. Small, yes but does a surpisingly good job on many little projects.
http://i57.photobucket.com/albums/g227/DBAviation/sander.jpg

Bill Pace
11-17-2007, 10:16 AM
Milton, you mean you've already got that disk?? Well, --- thats not good for the USPS reputation .... getting a package through that quick, What, 2----3 days, not bad, and cheap too.

Now,-- you KNOW you're required to take a pix of the finished sander, so we'll be waiting.

Since George & Graham shared their creations, I thought I'd slip mine in. This is from back in my heavy woodworking days and the plans were published in one of the mags. It incorporated dust removal capability, hence the covered motor -- if anybody has ever hogged a peice of wood on one of these, you'll KNOW the necessity of dust removal!!--- thats the hose going through the wall to be exhausted outside, and the table pivots, but I dont ever recall using it pivoted...

I do believe if somebody was gonna take all my tools and leave me 5 of my choice this would be included --- handy/useful tool.

http://i22.photobucket.com/albums/b301/pace1980/IMG_0714.jpg

DICKEYBIRD
11-17-2007, 12:14 PM
Mornin' Bill,

Yup, it was sitting on the counter when I got home from work yesterday. I was amazed too. Every time I've sent (or received) something via USPS lately, the service has been excellent.

Wow, your sander looks great! I'd call that one a "sanding station." Mine probably won't be as neat but should work OK. I'll post a picture when it's finished. It won't be right away as I was just "volunteered" to do a few gadgets for work plus I've got the "hots" to build a new ball-turner (tangential style.)