Belt/Disc Sanders

[ctwo]

After all this discussion about grinders, I remember hearing more than one folk suggest using a verticle belt sander is easier than a typical grinder to doing HSS bits.

After resisting the horror freight combo disc/belt, I've been looking on CL and see some old, larger craftsman brands at reasonable prices - ones on a table, stand, and belt driven, 9" disc, etc...and then there is the $500 rockwell types that I won't buy.

Is this likely going the right direction?

BTW, Enco has their Baldor KO tool grinder on sale for around two and a half bills, with green wheels...

[warmstrong1955]

I have a little Enco belt/disc sander. http://www.use-enco.com/CGI/INSRIT?PMAKA=163-4832
When I got mine it was $49.99.

Deburring & such....knocking off those sharp corners on things so I'm not bleedin'after I get 'em chucked up or clamped to the table....great little tool.
Sharpening things....notso much. Roughing, it's great, as other high dollar ones I've used. They just don't seem to do a good job as a real grinder when it comes down to that detail.....they tend to radius corners & edges a touch, that you don't want radiused..... I can't get those sharp angles quite right....if you know what I mean. May just be me.....

They are a worthy investment however.... I use mine a lot.

Bill

[lakeside53]

Harold's going to tell you that belt sanders make lousy HSS finishing tools as they roll the edge over a little. In my limited experience the extent of that really depends on the belt sander in use, and the blts. Mine at up to 6000sfm, 3m belts, and a precision backing platen does a fine job for 99% of the work, then the companion disk sander (just a big flat grinding wheel) is used to get the final (except for honing) finish. The advantage of the disk sander is that you can adjust the sfm by moving in or out from the center, and there is certainly no "roll over" effect.

$500 for the Rockwell? 6x12? buy it...

Chinese copy of the Baldor 500? well... if you do the required machining to true it up, it can be a decent machine. Throw the geen PAINTED concrete wheels into the garbage.

[Harold_V]

May just be me.....

No, it's not you. I've spoken out against the use of belt sanders for grinding tool bits numerous times. The harsh reality is what you said is spot on. The belt tends to bunch up just ahead of the contact point, so it slightly alters the relief angle, and can have a rounding effect, rendering the tool, for all practical purposes, dull.

There's nothing quite like using a properly dressed wheel for final sharpening, but using the belt to rough, assuming it lends itself to the tool in question, is just fine.

Harold

[Jors]

Here is a three part article that I have recetly read about the grinding of HSS tools. They make use of a belt sander. See third article.
http://www.machinistblog.com/grinding-l ... lt-sander/

Here is an post on how to upgrade a cheap grinder to make it usable:
http://www.machinistblog.com/modifying- ... -grinding/

[pete]

Personally I've got to agree with Harold about belt sanders and for the exact same reasons he's stated. For bulk metal removal while roughing in a new tool blank then yes, but just like he's pointed out they do round the tools edges. There's also a setup used by a lot of woodworkers and it's commonly referred to as the "Scary Sharp" method. This usually uses a thick piece of plate glass and various grits of emery paper and then automotive paint wet sanding very fine sandpaper. Usually down to 1,000-2,000 grit. However I'd still like to see some very high magnification photos of the cutting tools edges to see if there isn't some minor but important roll over on the tools edge due to that fine sandpaper raising up ahead of the cutting tool as it's being sharpened.

Along with all the info Harold took the time and trouble to post about sharpening HSS in The Resource Library sub forum here, I also tend to follow the recommendations for grinding wheels and stones stocked by most good woodworking supply stores. If anyone is fanatical about ultra sharp HSS tools it would be those woodworkers.

Pete

[ctwo]

Is there a particular size sander that would be better to look for? I'm thinking of the abrasives availability and cost.

I finished building a wooden box for my height gauge and plan to build a few more for some other tools and a belt sander would sure make nice work of the edges (my cabinetry skills are, not).

[warmstrong1955]

The little combo I have isn't much for woodworking.
My Dad was quite talented at cabinetry....using mesquite of all things. He had to find a lot of dead lot trees for him to build a kitchen table. Mesquite trees are generally hollow inside.

His sander had a 9" disc, and a 6" wide belt...not sure how long. Worked well for him, as he had to do a lot of sanding, after the bandsawing & planing.

Bill

[Harold_V]

Here is a three part article that I have recetly read about the grinding of HSS tools. They make use of a belt sander. See third article.

I read a portion of that article. Can't think of a better example to support what I've said about rolling the cutting edge.
Increasing relief angles was his solution to the rounded edges. Sort of like parking your car in the garage by driving through the unopened door. Seems to me the real solution is to do it right in the first place.

There's a serious issue in grinding tool bits without the hollow grind that one achieves with the periphery of a wheel. Give it some thought, and come to terms with why tool bits have been ground as they have.

Once a tool has been ground, it is customary (and advised) that the tool be stoned. That removes the rough surface created by the wheel, which, in the scheme of things, yields a better cutting tool, with a prolonged lifespan. A flat surface is difficult to stone, whereas a hollow ground tool is not. By grinding without chopping up the surface, the stone touches only at the top and bottom of the piece. Rounding is eliminated, and stoning happens almost instantly.

You guys can learn a lot form those who have gone before us. Picking up less than acceptable habits from those who fancy themselves clever can leave you wanting.

I've said it before, and I'm saying it again. A belt is no substitute for a wheel for fashioning a tool bit with proper geometry. A tool fashioned that way will not compete with one properly fashioned.

Harold

[JTiers]

I am 100% on-board with the "rounds over the edge" idea. they do..... not so much on the disc as with the belt... but they do.

That said, I've sharpened large drill buts by hand with a disc/belt unit, and they cut fine....

[Harold_V]

I am 100% on-board with the "rounds over the edge" idea. they do..... not so much on the disc as with the belt... but they do.

That said, I've sharpened large drill buts by hand with a disc/belt unit, and they cut fine....

I've done large drills on a belt, too, J. Not because I wanted to, but that's what I had at my disposal. You can limit the rounding by exceeding the recommended clearance angles, much like in the article that was mentioned. Much better than a worn or damaged drill, I'll admit.

Harold

[Howard Gorin]

On a belt sander, hold the tool bitup side down and grind from the botton to the top. No Rollover!