-
Welcome back Guest! Did you know you can mentor other members here at H-M? If not, please check out our Relaunch of Hobby Machinist Mentoring Program!
Sanding speed
- Thread starter Cobra
- Start date
i cant help you, but since you brought it up, i have some questions on the subject to add, if you dont mind. such as, what grit do you use for which metals? why are some units called metal sanders instead of grinders? if you could only have one or the other, would a belt grinder be a better choice than a bench wheel grinder? sorry for the hijack.
- Joined
- Dec 20, 2012
- Messages
- 9,408
If you have a variable speed grinder then there are some general guidelines: coarser belts can be run faster but once you get to 120 grit and finer you need to slow down for best belt life and performance. I am not sure of the SFM values. You might get a better answer on a knife makers forum.
I don't know what other guys do but I choose the grit for the job I want to do - coarser for shaping, finer for finishing. The finer the grit the more heat inherent in the process so you need to find out what grit works for the job you have at hand. I don't have separate belts for steel or aluminum; I grind both with the same belt but I will usually use a much finer belt to shape aluminum than I would for the same job in steel.
Belt sanders that grind wood are belt sanders, while those that cut metal are belt grinders. The latter generally have totally enclosed, fan cooled motors to prevent the ingress of metal dust.
As for which to have if you can only have one, it depends on what you want to do. Some folks are passionate about grinding lathe tools with a grinder, others prefer belt grinders. The advantage to general purpose belt grinders with flat platens is that the edge of your work piece is flat, not concave. For profiling and sheer speed it is hard to beat a belt grinder. The other advantages to a belt grinder is the ease with which you can change grits, no dressing to do and no risk of your belt exploding into shrapnel.
I suspect most of us have both a bench grinder and a belt sander/grinder in the shop. I have both but my bench grinder is used once every several years, while my belt grinder is used weekly or sometimes daily. I grind lathe tools on my belt grinder and may use my bench grinder only for shaping gravers. I'm sure other guys use their bench grinders a lot more than me and with good reason - they work well in their hands. In fact, I would guess more guys grind lathe tools with a bench grinder than on belts but this is slowly changing. For me, I prefer the better precision, control and support I have with a belt grinder for tool grinding. For fabricating I never use a bench grinder - too slow, too hot, and concave edges.
I don't know what other guys do but I choose the grit for the job I want to do - coarser for shaping, finer for finishing. The finer the grit the more heat inherent in the process so you need to find out what grit works for the job you have at hand. I don't have separate belts for steel or aluminum; I grind both with the same belt but I will usually use a much finer belt to shape aluminum than I would for the same job in steel.
Belt sanders that grind wood are belt sanders, while those that cut metal are belt grinders. The latter generally have totally enclosed, fan cooled motors to prevent the ingress of metal dust.
As for which to have if you can only have one, it depends on what you want to do. Some folks are passionate about grinding lathe tools with a grinder, others prefer belt grinders. The advantage to general purpose belt grinders with flat platens is that the edge of your work piece is flat, not concave. For profiling and sheer speed it is hard to beat a belt grinder. The other advantages to a belt grinder is the ease with which you can change grits, no dressing to do and no risk of your belt exploding into shrapnel.
I suspect most of us have both a bench grinder and a belt sander/grinder in the shop. I have both but my bench grinder is used once every several years, while my belt grinder is used weekly or sometimes daily. I grind lathe tools on my belt grinder and may use my bench grinder only for shaping gravers. I'm sure other guys use their bench grinders a lot more than me and with good reason - they work well in their hands. In fact, I would guess more guys grind lathe tools with a bench grinder than on belts but this is slowly changing. For me, I prefer the better precision, control and support I have with a belt grinder for tool grinding. For fabricating I never use a bench grinder - too slow, too hot, and concave edges.
- Joined
- Nov 11, 2013
- Messages
- 28
Steel at 180 Bnh requires about 6500 SFM for grinding ...
HTH
Grit sizing will depend on hardness.
The SFM I quoted is for vitrified grinding wheels, but resin bond belts will react the same...
Might even be a bit more forgiving...
HTH
Grit sizing will depend on hardness.
The SFM I quoted is for vitrified grinding wheels, but resin bond belts will react the same...
Might even be a bit more forgiving...
I guess a lot of the "If you could only have one?" question is related to what kind of work you do. I have a couple of bench grinders, a 6" belt grinder with a 12" disc sander on one end, and a 1" belt grinder. I do a lot of light fabrication work and I find the 1' grinder is used more than the others. The 6" belt is a great tool for roughing, but is not as good as the 1" when you want control/finesse. I generally use the 1" for doing hss tools. The bench grinders are used occasionally. I have one set up with a de-burring wheel and that one sees a fair amount of use. The 12" disc still has the disc it came with 20 years ago. I never realized how useful the 1" would be until I got it at an auction. For the kind of work I do, that would be my choice if I could only have one, but for the kind of work you do it may be the wrong answer. Like so many things, it depends.
I am looking to buy a new 6" X 48" belt /12"disc sander.
I was looking at the options. I am considering a 220 volt 3 phase. So I can slow it down for sharpening. And just more versatility. Just wondering what you guys think?
BTW I am looking at the Jet. Also asking for input on your experiences with the jet or any other brand currently available.
I was looking at the options. I am considering a 220 volt 3 phase. So I can slow it down for sharpening. And just more versatility. Just wondering what you guys think?
BTW I am looking at the Jet. Also asking for input on your experiences with the jet or any other brand currently available.
I think having some electronic variable speed would be good and I will do that in the 2x72 I’ve done some work on. I have a 4x52.5 that I recently sped up from 2500 fpm to 4500 fpm and it’s much better for metal now. With a ceramic belt. There a 12” disc on it, the edge of which is at 10k fpm.
- Joined
- Apr 8, 2013
- Messages
- 2,041
I have a pair of 8 inch bench grinders. One is green wheel/wire wheel. The other is alum ox coarse and fine. I also have a 6x48 belt sander and a 12 inch bench disc sander. I rough grind my lathe tools on the bench grinder and finish them on the disc sander that has a tilting table with miter gauge. The disc sander gets the angles perfect. With a disabled hand and 73 year old eyeballs it takes me forever to grind a perfect threading tool but it takes under two minutes with the disc setup. (after rough grinding on the bench grinder)
Very nice epanzella. My eyes aren't getting any younger. That is exactly what I was getting at. The tilting table and the miter gauge should help lots. And with speed control it may even be easier and perhaps less heat involved as well.
I've pretty much decided to do the three phase with the phase converter.
I've pretty much decided to do the three phase with the phase converter.
