QUESTION: Benefits/advantages of variable speed belt grinder
RSS | Subscribe | Contact Us | Advertise | About Us
Results 1 to 8 of 8
  1. #1
    Join Date
    Mar 2011
    Location
    Bilbao, Spain
    Posts
    725

    QUESTION: Benefits/advantages of variable speed belt grinder

    Hello all,

    Long ago I put together a belt grinder. Direct drive, single phase, fixed speed. Works great even though a few things could be totally improved (may do it in a near future).

    The thing is that I have a spare 3kw three-phase motor and I was thinking about putting it in my belt grinder along with a VDF. It could be almost a bolt-in replacement (it will fit with little to no modifications).

    The VDF needs to be single phase input - three phase output and suitable for 3kW. I do have a 3phase service (380v) but I would like it to have single phase input, just in case I move it to another location with no 3ph. I only need the speed control feature but anyway I guess a VDF like this is not going to be cheap.

    So, after all this babling... the question is: What benefits do I get from a variable speed grinder? What speeds are used with which type of belts and for which materials?

    I use my belt grinder mostly for mild steel, some stainless, some aluminum, the ocasional wood (I make wooden spearguns and sometimes shape the stock with the grinder) and stuff like that. I have noticed that with wood I sometimes get burn marks and I think that running the belt at lower speeds may result in a better finish. What about polishing?

    Other than that, is it really worth it?

    Thanks!

  2. #2
    Join Date
    Nov 2009
    Location
    Pensacola , Fla
    Posts
    896

    Re: QUESTION: Benefits/advantages of variable speed belt grinder

    I say for the wood yes slower speeds are better, but with metal you are trying to remove metal so I'm not sure how much slower speed will help.
    DIY CNC Plasma table & CandCNC DTHC-IV MP 3100 Feather Touch option
    Hypertherm 65
    Everlast PT 256 EX Tig
    Miler 180 Mig
    13" metal lathe
    Mill/ Drill
    ECT, ECT,

  3. #3
    Join Date
    Mar 2017
    Location
    bar stool
    Posts
    2,085

    Re: QUESTION: Benefits/advantages of variable speed belt grinder


  4. #4
    Join Date
    Jun 2016
    Location
    Not there
    Posts
    2,772

    Re: QUESTION: Benefits/advantages of variable speed belt grinder

    Drill press and wood/FAST
    Sander and wood/Slow
    Opposite for metal.Drill slow/sand-grind hallasz and use ceramics or zirc. Use AL ox cheapos on wood
    Set up a pulley system for the sander similar to what cheapo drill presses have.
    Here

  5. #5
    Join Date
    Jun 2016
    Location
    Not there
    Posts
    2,772

    Re: QUESTION: Benefits/advantages of variable speed belt grinder


  6. #6
    Join Date
    Mar 2011
    Location
    Bilbao, Spain
    Posts
    725

    Re: QUESTION: Benefits/advantages of variable speed belt grinder

    Quote Originally Posted by acourtjester View Post
    I say for the wood yes slower speeds are better, but with metal you are trying to remove metal so I'm not sure how much slower speed will help.
    For grinding with higher grits seems like I get a lot of heat. Maybe it is because the belt is not cutting, or maybe because the belt is moving too fast. I don't know.

    Quote Originally Posted by Virgil5 View Post
    Thanks for the reference!

    Quote Originally Posted by Bonzoo View Post
    Drill press and wood/FAST
    Sander and wood/Slow
    Opposite for metal.Drill slow/sand-grind hallasz and use ceramics or zirc. Use AL ox cheapos on wood
    Set up a pulley system for the sander similar to what cheapo drill presses have.
    Here
    Good rule of thumb bonzo, along the lines of what I thought.
    I take good note on the belt suggestions. All I have now are aluminum oxide belts, and they seem to loose the grit easily.

    Problem with the pulley systems is sourcing the frigging pulleys paired with my lack of lathe, which does not allow me to do any adjustments (bores) to reuse existing pulleys. The cost of sourcing step pulleys + turning the bores to the correct diameter, pillow blocks for the shafts, shaft material, etc. easily would double the cost of a VDF for a motor I already have (for direct drive configuration).

    I have checked and I seems like I would be set for 150€. I can afford that no problem. I just need to check that my pulley bore matches the shaft in the 3ph motor I want to use.

    Regarding the video, it amazes me how he achieves parallel plung lines on both sides of the bevel without any kind of a stop/guide... I have some stops made and Y use them agains the platen (all I do is flat grinding, I don't have any contact wheels)

    Quote Originally Posted by Bonzoo View Post
    Nice video, although I tend to set the piece on the ground (on top of some wood), attach the side handle, lock it between my ankles and use my body weight on the drill. Closest thing to a drill press you can achieve with a hand held drill.

    On a side note, on Monday I was at the shop m messing arround and I had to grind some rubber. I used a loaded/not sharp belt. And all of a sudden, the belt looked like new again. So I will look into those cleaning blocks made or rubber to refreshen the belts.

    Mikel

  7. #7
    Join Date
    Mar 2017
    Location
    bar stool
    Posts
    2,085

    Re: QUESTION: Benefits/advantages of variable speed belt grinder

    Speed + feed will either help you or hurt you.
    Learn to think of cut speed, particularly in grinding in feet per minute of engagement, NOT RPM. A large wheel traveling slow RPM will usually deliver more FPM than a small wheel at high RPM.

    Heat is always the enemy. The trick is to find where it is coming from and minimize it.

    In belts it's easier to generate heat, and that heat kills the belt. Since you mention loss of grit, look at your belts under magnification. Are there cutting edges or rounded pebbles that generate heat and cause abrasive to detatch from the belt?

    I'll also toss out the possibility of a varispeed pulley in the drive. They are quite common on industrial buffing lathes, because precise adjustment of FPM is recognized as a critical factor to outcome.

  8. #8
    Join Date
    Jun 2016
    Location
    Not there
    Posts
    2,772

    Re: QUESTION: Benefits/advantages of variable speed belt grinder

    Link belts an pulleys.
    Call these guys and be done with it
    http://www.fennerdrives.com/powermax/pulleys_idlers/

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
RSS | Home | Penton Media | Contact Us | Subscribe | For Advertisers | Terms of Use | Privacy Statement