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Thickness Sander Questions
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Author:  JimWomack [ Tue Dec 04, 2007 8:42 am ]
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Looks like I may have a couple of weeks off before the holidays so I thought I might break down and build a thickness sander during that time. I have a pretty good idea about what I'm going to do but I did have two things I'd like to run by those that have rolled their own. My drum will be 4-5" in diameter and 20-22" wide. First, what size motor would get the job done? I was thinking something along the lines of 2HP... maybe something bigger? Finally, what size shaft would you use for the drum? I was thinking I would go 7/8". Is that overkill or would 5/8" do it.
Author:  PaulB [ Tue Dec 04, 2007 9:57 am ]
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If you're making one 22" wide, I'd go for the thickest shaft you can afford.

The easiest way to build these things - from a working out the speed of the motor/drum diameter/pully size. Is to buy the motor first. I used a 1 1/4 hp motor that works at (I think) around 1425rpm. This seems to have plenty of power and has never bogged down in the 4 years or so that I've been using it.

Once you have the motor (I pulled mine out of a discarded vacuum pump), have a look at the drum speeds of the commercially available thickness sanders and try to match those with easily available pullies (I had to have one machined out to match the shaft dia). Once you have pullies and motor and a drum speed to aim for, you tailor the dia of the drum to get the numbers (ft/min of sandpaper) you're after.
Author:  KenH [ Tue Dec 04, 2007 1:01 pm ]
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I dont know if this will do you any good, but the Performax 16/32 sander is a 1.5 hp 825rpm motor and the drum size is about 1 1/2" in diameter. It is direct drive with a coupling similar to a lovejoy coupling.


If I were building one, I would build it at least 18" wide.
Author:  old man [ Tue Dec 04, 2007 2:43 pm ]
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Mine is 4" diameter and sands 22" wide. I used a 1 1/2 hp motor, I think it is 1725. I'm running it with 1:1 pulleys, and it is at the perfect speed for me. I used a 5/8" shaft, which is plenty strong for what I do. Mine works great. There are folks here who frown on home built sanders, but I'm very pleased with mine. I also use velcro backed paper on it.

Ron
Author:  Dennis Leahy [ Tue Dec 04, 2007 3:56 pm ]
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Hi Jim,

You might want to look on Ebay for "pillow block bearings", and see what you can get a deal on, and let that determine the shaft diameter. Ron, I'm surprised that 5/8 doesn't flex, but I believe ya! Still, in the one I'm building, I'm using a 1" shaft. You'll have a difficult time getting the correct pulleys/sheaves on Ebay. Check McMaster Carr and Grainger for pulleys.

I found an unused, surplus, 3HP, 220V motor that is probably overrated - probably closer to 2HP. Should be more than enough.

I went with a 6" drum, thinking that the bigger the drum, the more surface area, and hopefully that will both cool a little faster and clog less.

Dennis
Author:  JohnAbercrombie [ Tue Dec 04, 2007 5:18 pm ]
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Jim-
When planning the width, it's a good idea to assume that you'll probably lose an inch or so on each end with tape wraps or paper hold-downs of some sort- keeping the paper on the drum has been my main problem.
So if you want to be able to put backs/tops through sideways (cross-grain sanding is better with gummy woods like rosewood), keep this in mind.
I'd use a pretty hefty shaft- I've got 3/4 on mine.
I also use direct drive with a 1HP motor- it seems to work fine with an 8" drum- you don't hog wood off with these things anyway- so lots of different motor/drum size combos seem to work..


You'll wonder how you ever did without a thickness sander, once you get yours done.

Cheers
John
Author:  old man [ Wed Dec 05, 2007 5:37 am ]
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No flex that I can detect. I really wouldn't expect any. My drum is solid with only about 1" of the shaft between the end of the drum and the pillow block. It would take a mighty force to flex a 1" section, I think. I could be wrong, though.

Ron
Author:  old man [ Wed Dec 05, 2007 5:38 am ]
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Actually, I only have about 1/2" of shaft between the drum and block.

Ron
Author:  Howard Klepper [ Wed Dec 05, 2007 6:59 am ]
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It's right about at this point that Rick often makes a comment about whether you want to be building guitars or machinery, when there are factories that do the machinery much better than you ever will.

On the other hand, Rick has a long list of orders to fill, and Jim may just like making machinery.
Author:  FishtownMike [ Wed Dec 05, 2007 7:20 am ]
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I started a post a couple of weeks ago with basically the same idea. Rick made the comment just like you said and I came to the conclusion that Rick is right and bought a performax 10-20 instead and I'm sure happy i did. I rather tinker with building guitars for the two weeks it would have taken me to build the sander.
Author:  PaulB [ Wed Dec 05, 2007 9:08 am ]
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Some of us have to get approval from the missus before we can go out and buy a performax 10-20 or whatever. I never would have had a thickness sander if I didn't build it myself. Every spare cent we have goes into the house renovation.

I pretty much scrounged all the materials including shaft, pillow blocks, pullies, and motor. About the only thing I had to pay for was getting a pully machined out to match the shaft. I think it only cost me around $20 - $30 dollars all up. Much easier to get something like that under radar.

Mine doesn't have a powerfeed, but I ran a digital caliper around the perimiter of a joined top I had thicknessed on my machine, I couldn't see a difference in thickness anywhere - at a resolution of 1 thou. Not bad, and certainly close enough.

You can build your own, and it will rival the comercial models in accuracy. But then, I have as much fun building machines as I do building guitars.
Author:  JohnAbercrombie [ Wed Dec 05, 2007 12:05 pm ]
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[QUOTE=Howard Klepper] It's right about at this point that Rick often makes a comment about whether you want to be building guitars or machinery, when there are factories that do the machinery much better than you ever will.

On the other hand, Rick has a long list of orders to fill, and Jim may just like making machinery. [/QUOTE]

Good point, Howard.

Certainly, if you had to go out and buy a good new motor and a long list of parts, a Grizzly (or similar) starts to make good sense. If you have a well-stocked 'parts collection', though, you can get going for under $100 with a homebuilt.

Also, this is a good time for y'all in the US to buy up the imported tools that are in inventory, before the falling dollar boosts all the prices for imports. So, something like a Grizzly at $900+ starts to make a lot of sense right now.

Convincing the kids that they don't need presents can be a tough sell at this time of year, though!

Cheers
John
Author:  Alain Lambert [ Wed Dec 05, 2007 1:15 pm ]
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I do not want to hijack this tread, but I am looking to add a powerfeed to my sander.
Anyone has a good plan/solution for that?
Author:  JimWomack [ Wed Dec 05, 2007 1:55 pm ]
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Lots of good information, thanks. I decided to go with the 3/4" shaft. I'm sure that 5/8 would probably work OK if the distance between the end of the drum and the bearing was small, like Rons but the difference between the 5/8 and 3/4" stock was just a few dollars so it seemed like a no-brainer. I have a horse and a half motor I took off a compressor some time ago
and I think I'll go with that instead of buying something more
powerful... at least for now.
Thanks for the Ebay suggestion, Dennis. Found a quality pair of 3/4" pillow block bearings for a third of what the local hardware was selling them for.
John, I am interested in your direct-drive arrangement. Just curious where you got the coupler. Kicked around for a bit on McMaster-Carr, but didn't see anything like that... could have missed it, though.
As for building or buying, I'm kinda in Paul's boat. Don't think my wife would buy into it right now. And I do get a kick out building tools, jigs, machines, etc. A while back I built a scratch-start DC TIG welder using a truck alternator, just for the heck of it... even though I had a nice Hobart in the barn. Except for the shaft and bearings, I pretty much have everything else I need, so this will be a very inexpensive project, so that's a plus.
Again, thanks everyone.
Author:  JohnAbercrombie [ Wed Dec 05, 2007 3:25 pm ]
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Jim-
If you search on 'Flexible coupling' on McMaster Carr, you should find what you need.
Pg 1115: Flexible Spider Shaft Couplings
You buy a hub sized for each of your shafts, and then the rubber spider that goes between them.
It's probably cheaper than buying two good pulleys and a link belt. It makes the sander wider, but I managed to mount my disc sander and spindle-style sander on the same stand, so it all works out for me.

I just used a grinder and file to make the keyway in the sander shaft- wife wouldn't go for the milling machine for one job!
I got my connector (and the pillow blocks as well) from Princess Auto, here in Canada.

My first thickness sander was built from GAL Data Sheet ideas, back in the 70s- I used direct drive on that as well, with a piece of auto heater hose and a couple of hose clamps for the coupling (!). It worked fine, actually. That one also had a neat 'wedge' arrangement for adjusting the table- a threaded rod pushed the table 'forward' and it climbed up 4 wedges- very stable, though it didn't have a big range of adjustment.

Another hint- don't make your table too long if you are going to hand-feed the stock. By the time you want to grab the stock on the outfeed side, it's nice if it's overhanging the edge of the table.
Also, make your dust hood nice and close to the drum- it helps with the airflow and lets you hand-feed shorter pieces more easily- I don't let my fingers get under the dust hood; that's the 'red line' for me.

I made my drum from circles of misc scrap plywood and MDF/particle board, epoxied together along the shaft. If I were doing it again, I'd make a jig to drill (symmetrical) holes in each disk before assembly to make the finished drum lighter- I think it would make vibration problems a little easier to solve.

Building tools and jigs is fun for me as well. If you just focus on 'building guitars' you've started on a slippery slope- next stop is farming out guitar parts to be CNC'd...

Drop me a pm if you need more info.

And, we all wanna see your machine when you get it done!

Cheers
John
Author:  Daniel M [ Wed Dec 05, 2007 4:16 pm ]
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I used a 1" shaft with a stacked MDF & plywood disc drum It's very rigid.
However, If I was starting from scratch I would buy a 25" replacement drum from Grizzly. I priced them out last year & they are around $100.00.
My home made drum is 25" long. After losing 3/4" on each end where the paper is taped in place, I'm really glad I didn't make it shorter.
Author:  douglas ingram [ Wed Dec 05, 2007 5:12 pm ]
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Princess Auto is great! And head office is just down the road and 'round the corner, too.  Well sort of...but I can be there in about 20 minutes.

www.princessauto.com
Author:  David Collins [ Wed Dec 05, 2007 5:15 pm ]
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I rarely step in to conversations like this but....

Filippo, I think you may have skimmed Howard's post too quickly and
perhaps misunderstood. What I read was:

"It's right about at this point that Rick often makes a comment about
whether you want to be building guitars or machinery, when there are
factories that do the machinery much better than you ever will."

- In other words "From a pure business and financial standpoint it is
more economical and efficient to buy a pre-existing tool when one is
available, devoting time that would have been spent in creating that tool
toward work in you own trade, at which you are more efficient."   - just
some business economics.

"On the other hand, Rick has a long list of orders to fill, and Jim may
just like making machinery."

- In other words "That advice is sound from the perspective of a
professional luthier who is already backlogged to the gills with guitar
work, while for a hobbyist or even a professional who takes great pride in
crafting their own tools, go for it. There's nothing wrong with doing what
you like."



A misunderstanding of Howard's intentions I believe, though the personal
jab was a bit harsh and hasty I think. Anyway, que sera, sera. It's done.


Now, please everyone do me a favor, and talk about thickness sanders. I
think this can be dropped entirely. No more posts about this, Please.

-----------------------


By the way, I think you're right on with a 7/8" shaft, and a 2HP drive
motor should be plenty. If it's too much for the motor to handle, you can
always just slow down the feed.
Author:  Arnt Rian [ Wed Dec 05, 2007 6:59 pm ]
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Keep also in mind that there are members here from many different countries and for some of us these smaller drum sanders are few and far between and priced accordingly. For instance, here in Norway the only ones available ones that I have found are the Jet 10/20 for $1700, the 16/32 for $2500! A company is selling a Chinese drum sander for $1000, but it cheap in every respect. On the other hand, used reconditioned industrial wide belt sanders machines are much more common, and some of the smallest models (600 mm / 24”) are quite reasonably priced, at least when you consider how much more efficient they are. I’m sure members in other counties have their own unique circumstances, and home made sanders may make sense for them than (some of) the North American members.

I made a simple drum sander with a 660 mm x 150 mm (26" x 6") drum; it is powered by a 1.1 kW / 3ph motor and accurate to 0.1 mm. The shaft is 35 mm (1 3/8”) and certainly sturdy enough, but I happened to have it laying around. I only use it as a finish sander to take off the last 0.5 or so, unless the wood is too difficult to hand plane, and then I will use it as a thickness sander. Tops I usually hand plane.

These are simple machines and do not to be elaborate to work well, but a good dust collection system and quality paper is a must. I use the same Velcro backed Klingspor paper as Ron.
Author:  JimWomack [ Fri Dec 07, 2007 2:37 am ]
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Well, I've hit a small snag. Seems the motor that I was going to use is shot. I've found 2 more motors that I can have for basically nothing. One is a 1/2 HP, 1725 RPM motor . The other is rated at 3 1/2 HP and 3450 RPMs. I'm guessing the first is too small to be practical. I'll probably go with the second. I was considering using a direct-drive system like John's. I'm thinking that 3450 RPM is probably too fast to turn a wooden drum (safely). What do you think? I could always go to v-groove pulleys to reduce the RPMs at the drum.
Author:  Bruce Dickey [ Fri Dec 07, 2007 4:00 am ]
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Ebay has electric motors cheap.

I think you'd have a problem with either of those half or three and a half.

I bet you can have it sitting in your shop in a week.
Author:  JohnAbercrombie [ Fri Dec 07, 2007 5:31 am ]
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Jim-
Since you are in the US, where shipping costs are not such a big deal, eBay may be a possibility for a good motor. I've looked a few times and never found anything that made sense for me in Canada- your luck may differ.

3450 rpm is probably too fast- that's what I'm using with an 8" drum and I've got some vibration, though I'm not sure it would disappear with a slower speed motor. The too-high speed probably contributes to problems with the paper loosening as well. I think I'm way higher than the recommended fpm numbers for sanding. However it seems to work OK, and I'm happy with it. You'd have fewer problems in all the above categories with the smaller drum.

In your place, I'd go ahead with the bigger motor and just make sure I could bolt a smaller 1725 motor in its place (with shims/blocks) if I decided to get a replacement later from eBay. But then, I don't like to wait around to finish projects for too long. When you're buying your coupler, it might be a good idea to get a spare 'motor end' to suit a 5/8 shaft (for that possible eBay motor), since I'd guess that your 3.5 HP has a larger shaft.
Check that you can wire the motor for CW or CCW rotation, or make sure that you hang the motor off the appropriate end of the drum.

Cheers
John
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