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Why do 6x48 belt sanders/grinders for metal seem uncommon?

PNW Bachelor

Plastic
Joined
Feb 9, 2022
I have a common old Craftsman belt/disc sander which--although I do both woodworking and metalworking--I use almost exclusively for metalworking. Grinding welds, prepping parts, cleaning up bandsaw cuts to make a square face with brushed finish.

Recently, I've decided to seek higher performance machine (i.e. higher speed, primarily), but almost all the recommendations are towards the popular 2x72 3-wheel models, which seem good for knifemaking etc. I'm sure these are great for many uses; but I rely on having a larger, adjustable-angle support table against a semi-flat platen. Am I doing it wrong? Is this just not how others use their belt sander/grinders?

If I stick with the belt/disc form factor but want a higher speed, the only option I see in consumer models is the G1183 from Grizzly, with a belt-speed of 5000sfpm. This might be the best option, but I wish this model came with a cabinet.

I don't see any other options for moving a 6" belt at high speed until you step into commercial manufactures at well over $2k; everything just seems geared toward woodworking, at lower speeds; so I ask myself again--why am I the only one who seems to want a 6x48" sander for metalworking? (and, I'm probably doing it wrong!)

A used heavy-duty floor unit with 3-phase and a VFD would be ideal, but I probably can't wait for the right model to appear.

Thanks for the advice, forum!

Bonus round: I have a 20" variable speed Powermatic Bandsaw which turns at about 40 to 4000 RPM. Could I put a 1"x150" sanding belt on that for detail work (in the style of all the narrow belt sanders which seem so popular now). No contact wheel or platen, I guess.
 

Bondo

Hot Rolled
Joined
May 14, 2011
Location
Bridgeton NJ
I have 4 kalamazoo 6x48 belt sanders, 1 with a 12" disc. I also have 2 4x36 for tungsten sanders.

They work well, but I also just purchased a 4x90 kalamazoo belt sander.

I have so many so I dont have to change out belts often. I keep different grits on each one.

The 4x90 is a heavy hog when I need heavy removal on stainless.

I have less then $1,000 into all my sanders except the 4x90.

Sent from my SM-G960U using Tapatalk
 

Vecair

Aluminum
Joined
Feb 19, 2017
Location
Prescott
I have an old 6x48 Powermatic that cost 300 bucks, came out of a metal working factory, even has its own vacuum, second best machine I have. I also have a old variable speed 6x48 that I ditched the VS gear and repullied it for slow speed for metal. Can't beat them for metal work! Find an old one at auction if you can.
 

Blazemaster

Hot Rolled
Joined
Oct 13, 2009
Location
Olympia, Wa
I have also noticed this. I have a delta 6x48 with a 12" disc and use it quite often the same way you do. I also have a 14" pedestal grinder I use often. My best advice is look for a heavy older model in good shape, or one to fix up if you have patience/time.

I haven't tried the 2x72 knife style grinders, but they seem to remove a lot of material. Just spendy.
 

L Vanice

Diamond
Joined
Feb 8, 2006
Location
Fort Wayne, IN
I am on my third 6 x 48/12 sander/grinder since the first one around 1965. The current one is Japanese, bought new around 1990 for about $500, which was cheaper than the big Rockwell machines at the time. It has a direct drive motor, so it can sit on any bench. I have it on a rolling steel office cabinet with storage for belts and discs. Over the decades, I have found that my Rockwell 1 x 42 belt sander/grinder is the one I use about 98% of the time because I seldom do large work.

I see Jet has some big sander/grinders similar to mine, but I suppose they are Chinese. There are used Rockwells around that might still be in OK shape, but replacement parts would be scarce.

Larry
 

PNW Bachelor

Plastic
Joined
Feb 9, 2022
Thanks for all the input; relieved that I'm not the only one who likes this form factor for general metalwork.

BELT SPEED: how fast are your machines running for metal--e.g. mild and stainless steels? Every belt/disc unit I see from the likes of Powermatic, Jet etc run at 1700-2500 feet/min, and I've been reading that double that is better for metal (And--has anybody seen the videos of the Fireball gocart belt sander running at 9000sfpm? :smoking: That grizzly unit I mentioned is the fastest consumer model I found at 5000 sfpm, which is making it very attractive right now as I am in middle of shaping a bunch of parts from 1/2" stainless plate.

If I found one of those cabinet, belt-driven units, I could repower with 3ph and a VFD for higher (and variable) speeds; but I'm guessing that would add $600 to the price.

How important is variable speed for different materials?
 

DDoug

Diamond
Joined
Oct 18, 2005
Location
NW Pa
Along with speed, H.P. per inch of belt width is a number the professional units address, check 3M for suggestion.
 

Bill D

Diamond
Joined
Apr 1, 2004
Location
Modesto, CA USA
I would say metal workers used grinding wheels for hundreds of years before sand paper belts got invented. By the time belts got invented shapers could flatten metal faster then sanding. A surface grinder is also faster then sandpaper that has to stay cool enough not to have glue failure.
Bill D
 

BT Fabrication

Hot Rolled
Joined
Nov 3, 2019
I have an old 6x48 for the shop, picked it up when i went to look at a bridgeport couple years back and got that instead for $20 and a full box of 99% nickel rods for $50
 

macgyver

Stainless
Joined
Aug 2, 2012
Location
Pittsburg, KS
I have a mid 60's green Powermatic 6x48 belt and 12" disc combo. It is 3 phase factory with the vacuum collector. It is belt driven so even if you don't get a 3 phase with vfd, I'd think you could change belts to a specific speed without much effort.
I paid more than I'd like at $450 but I needed it immediately and it was here in town. I see them often in the $300 range ready to go.
 

dgfoster

Diamond
Joined
Jun 14, 2008
Location
Bellingham, WA
If you really think you have to have a 6 inch belt width, fine and dandy go for it. However 2 by 72 belt grinders offer several advantages I think. One is the supply and huge variety of belts . Because these are very popular models, belt supply is very broad and pricing very competitive. Secondly certain designs of these are very versatile. I recently built in Jer Schmidt belt grinder. I used plans that he sells on Etsy. I think his plans are great except for the method he uses to fabricate square sleeves which is not a good method. I won’t write a lengthy discussion on that subject but I would not recommend following his suggested fabrication method. The belt grinder was not cheap to build. I suspect I have at least $1500 into it. But with the 2 hp motor and totally enclosed good quality variable frequency drive and the amazing utility of this design I have no regrets. I think building something along the lines of Jer’s design is an excellent idea and offers much more utility than a simple three wheel grinder.

At least look at the design and listen to his video where he demos and discusses his design.

Inch Plans Gen 2 Tilting Belt Grinder | Etsy

I have no connection to him other than as a happy customer of his design. I mounted mine on tool chest top that also serves to transport and store a 24X36" granite surface plate.
Finished.jpg

I use it daily and usually many times daily. With a good belt you can hog off steel or cast iron at 6000 SFM (ideal) or slow it down for acrylic to a few hundred SFM. Very smooth.


Hogging off 1" angle using 60 grit cubitron


Denis
 
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crossthread

Titanium
Joined
Aug 5, 2004
Location
Richmond,VA,USA
I bought a Balder 1 X 42 bench top sander some years back and I don't know how I ever got along without it. I truly use it every day. I recently bought some 10 micron diamond belts and they will really put an edge on something. I also have a 6 X 48 sander with the disc on the side. I must say I don't use the disc sander much but I use the belt part quite a bit. It is actually made for woodworking I think but it does a really good job on deburring long edges and the platten keeps everything nice and straight. I really wouldn't want it to go any faster. The only improvement I made was to add some anti friction pads on top of the platten. These are made for this purpose and cut down on the heat generated by the friction of the belt which seems to prolong the life of the glue joint tremendously. They are gummy on the back and you just slap them on the platten.
 

M. Moore

Titanium
Joined
Jun 8, 2007
Location
Vancouver Island, B.C. Canada
I have a 4” vertical wet sander that I adapted from a glass grinder. Took all the glass rollers off and added a table and larger platen. Wet sanding works well but is a bit messy. I use straight water so it does rust a bit but is the best for grinding. My belts last a long time with the wet sanding and I have never had one break at the seam. I do tear them fairly often if I move my part into the platen too quickly by accident.
Glass is sanded at a much lower sfm than steel so I upped the speed and increased the HP, 3 hp for a 4” wide belt is just enough for heavy hogging.
The main drawback is the loud sound of it running. The design of the cabinet causes a drum resonance that is very loud. The second drawback is the build-up of grinding swarf in the cabinet. It seems to somehow weld itself back into almost solid steel with the water. I use a pneumatic hammer with a chisel to clean off the swarf but need to be careful that the chisel doesn’t punch through the thin sheet metal cabinet.
The biggest plusses are that there is very little dust in the air when grinding and the water really helps keep the part cool.
Sometimes the old glass grinders can be had for cheap but they are slow and underpowered. It was well worth it for me to modify my machine as I use it a lot and particularly like having a table that is square to the platen. I just can’t imagine how a round ended belt grinder is useful when you are holding your part in mid air? Like a Gallant rotobelt machine. Some parts I grind are heavy so why would I want to be fighting gravity while trying to do a finesse job of edge treatment?
 

metalmagpie

Titanium
Joined
May 22, 2006
Location
Seattle
I have long believed that 6000 sfm was a good top speed. I just saw the fireball tool video where he runs his belt at 9000 sfm. His belt didn't fly apart and it really hogged off metal. Anyway, I believe that variable speed is mandatory if you ever want to do gentler work like running fine grit belts.
 

dgfoster

Diamond
Joined
Jun 14, 2008
Location
Bellingham, WA
Sometimes the old glass grinders can be had for cheap but they are slow and underpowered. It was well worth it for me to modify my machine as I use it a lot and particularly like having a table that is square to the platen. I just can’t imagine how a round ended belt grinder is useful when you are holding your part in mid air? Like a Gallant rotobelt machine. Some parts I grind are heavy so why would I want to be fighting gravity while trying to do a finesse job of edge treatment?

What you are saying concerning a platen and square table has merit as the majority of the time a belt grinder will be used to grind squarish faces on metal. But, there are also plenty of occasions where an angled face is needed and it is particularly helpful if a table can be set to that angle. And not always are the surfaces needing grinding flat surfaces. These needs to my suggestion to not get a simple 3-wheel (with fixed table) design. The design I suggested above includes provision for changing out belts AND tables and platen for contact wheel and small contact wheel attachments in seconds. The spring-loaded silver lever in the photos above is a combo tracking and tensioning lever that allows changing belts in less than 30 seconds. I made the recommended fixed 90 deg trable and the variable angle table, flat platten, slightly arched platen, large contact wheel and small contact wheel attachments. In a lot of commercial and shop-fabricated grinders exchanging these features is cumbersome and time-consuming (read that as not likely to be done unless there is a big need), but in this design exchanging them is quick and painless. And switching from vertical to horizontal mode which is especially useful for long parts takes 15 seconds with no change in table height needed.

I don't use the small contact wheel attachment often in my shop. But when I need it it does work that no othere grinder in the shop can do. Same for the curved platen---not often neeeded but nice when you want it.

Here is the small contact attachment that accepts "wheels" down to 1/2" diameter.


Tilt table attachment under construction:
Tilt table.jpg

My apologies if I'm beating the drum to hard on this.

Denis
 

richard newman

Titanium
Joined
Jul 28, 2006
Location
rochester, ny
As a woodwoorker, this is interesting, as I occasionally grind hss pattern knives for my shaper. 5/16" or 3/8" thick, 1" to 3" wide. Can be a lot of steel to remove, been cutting as close as I can with an abrasive cut-off saw, then to the grinder.

Questions: would one of these belt sanders be a lot faster than an 8", 3/4 hp, 3500 rpm bench grinder? Is it just a horsepower thing? What kind of belt would be best to hog material off?
 

Dan from Oakland

Titanium
Joined
Sep 15, 2005
Location
Oakland, CA
Richard- we use the blue Norton Zirconia abrasive belts and they are amazing- nothing like the old aluminum oxide abrasives. The Zirconia abrasive cut fast and cool and lasts abot 10 times longer than AO.
 

LKeithR

Stainless
Joined
Sep 1, 2011
Location
Langley, B.C.
Richard- we use the blue Norton Zirconia abrasive belts and they are amazing- nothing like the old aluminum oxide abrasives. The Zirconia abrasive cut fast and cool and lasts abot 10 times longer than AO.

Yup, the blue zirconia belts are really good. We use a european brand (which I think is better
than anything Norton has to offer) and get good service and life out of them.

We have a 6" x 48" Grizzly sander which is totally reliable, rugged and set up so you can easily
change belts. We've had it for nearly 20 years and it has served us well. I took the disc off as
soon as we got it--never used it at all...
 








 
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