Speed Control for General Mortiser
user-169767
| Posted in Power Tools and Machinery on
I realize that a cheap speed control, for a router e.g., cannot be used for a 1/2 hp mortiser. I assume that I need a VFD or something similar. Has anyone found, built or come up with a speed control that can be used for the General 1/2HP hollow Chisel Mortiser. I find that 1725 RPM is too fast for extremely hard wood such as beach.
Thanks
Replies
"I assume that I need a VFD or something similar."
Or, if the motor is belt-driven, some different pulleys. The speed of an induction motor is controlled by the line frequency and the internal geometry of the windings; there's no other way to change it. And unless the motor is 3-phase, a VFD-enabled induction motor can only operate over a very limited range. For true variable speed you need a universal motor, which either has brushes and screams like a banshee, or is electronically commutated and costs more than the rest of the machine.
You might be able to find an 1150 rpm motor of the same frame size as the one you have. It would then be a drop-in replacement, although it's obviously not something you could swtich in and out at a moment's notice.
-Steve
These folks have one.
Here.
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It would indeed be a tragedy if the history of the human race proved to be nothing more than the story of an ape playing with a box of matches on a petrol dump. ~David Ormsby Gore
Sorry but thats three phase, we have them in the UK.
Mufti;
It is a single phase unit. Here is an excerpt from the technical sheet.
OPTIDRIVE E1Easy to use, low power, low cost1AC Variable Speed Drive 1/2HP - 1 /2HPRich in features the Optidrive E1 is the mostcommercially competitive variable frequencydrive in the Optidrive family. The product isdedicated to low power single phase applicationswhere price is important.------------------------------------
It would indeed be a tragedy if the history of the human race proved to be nothing more than the story of an ape playing with a box of matches on a petrol dump. ~David Ormsby Gore
Ordinary single phase motors, like those on a mortiser, can't be used with a variable speed drive because the centrifugal starting switch would kick in at the low end of the speed range causing the start windings to burn up after a minute or so.
John White
I could be wrong but I don't believe my mortiser or drill press have centrifugal switches. I think they are capacitor start/run motors with two windings and a cap but no switch.------------------------------------
It would indeed be a tragedy if the history of the human race proved to be nothing more than the story of an ape playing with a box of matches on a petrol dump. ~David Ormsby Gore
I've never seen a larger motor, with a capaictor, on a woodworking tool that didn't have an internal start switch, but I can't claim that is always the case. What is the make and model number of your mortiser, I'll try to find out.
John W.
I could be all wet, it's a Delta 14-651.
I didn't pull it apart to check, it works fine and I never felt the need to slow it down! I was going by the sound of the motor starting and stopping, after years of listening to motors the sound of the switch is usually pretty noticeable. Also I couldn't see a reason for high starting torque in this application, there is virtually no load on the motor at startup so one would only need to establish a rotating field to get it going.
It seems like a switch would add unneccesary expense and complexity and would not be economically advantageous for the manufacturer.
But like I said, I could be all wet!!------------------------------------
It would indeed be a tragedy if the history of the human race proved to be nothing more than the story of an ape playing with a box of matches on a petrol dump. ~David Ormsby Gore
The optidrive is a single phase unit but it only works with certain type of single phase motors. It will not work with capacitor start or capacitor run type motors. Split phase was one they mentioned and shaded pole I believe.was the other. Just got off the phone with them.
Did they say how low a speed you can achieve? The online data sheet doesn't mention it, and I would think that there would be a point at which the torque drops off dramatically.
-Steve
I didn't get that deep on the discussion with the rep. I'm betting it's not any different from a three phase VFD. You can only go so low before it looses power. If you look at most lathes with VFD's, they have 2 pulleys to go from hi to low range.
Rick,
I wouldn't call them inexpensive either!
Regards,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
I had found one that wouldnt affect the longevity of the motor, but as Steve says, it cost almost as much as the machine. The reason I considered it was I have been using mine as a drill press. I had a machinist make a 1" dia threaded rod milled to suit the mortiser chuck and has a threaded end to accept a typical chuck. Works great, but a little too fast.
Brad
Brad,
The reason I considered it was I have been using mine as a drill press.
You must be a mind reader. I thought about doing that just this past weekend. There have been many times that I wanted to use the drill press that I have but with limited space in the woodshop was toying with the idea of using my hollow chisel mortiser as a drillpress.
Any thoughts/suggestions? I believe that mine will swivel so as to allow use all the way to the floor, with a fixture added. It's mounted on one side of a thick maple slab right now. It would be nice to be able to multi-function it.
Regards,
Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Edited 1/15/2008 11:39 am ET by KiddervilleAcres
Its pretty easy to do. I will take a pic of the piece I had machined. All you really need to do is add a chuck below the head. I started with a 5/8" fine thread bolt (cut off the head) with a chuck bolted to it, but it was too flexible and bolts are not machined to a tight enough spec. The next one I built works great, but the speed of the mortiser can be tricky.
Brad
Brad,
I'll start a new discussion in the Power Tools section so as to not to hijack the OPs discussion.
Regards,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
David,
I can't give you an answer to your question on obtaining a speed controller for that motor.
However, I believe that if you find 1725rpm too fast for Beech then there there is a different problem; namely that your set up of the chisel and augur may be faulty or that the augur or chisel or both are not sharp enough. Another possibility is your technique- the thing needs to be plunged in decisively and not allowed to hover .
I have a Multico MCD type which runs at 2850 rpm which is on the fast side for bigger nortices such as 15mm plus, but one can manage even those woods which burn easily such as Wenge and Rhodesian Teak-provided all is set up properly.
I think you should be able to go through that Beech like butter - 1725 rpm is not that fast. Maybe we could help more if you showed pictures of your augur and chisel.
Philip. Thanks for the note. I have reviewed what my set up has been and now I think that issue is not with the chisel, but the auger bit. I am using the ones that came with the tool. I have decided to purchase the high end chisle and bit set from Lee Valley, which I have heard are quite excellent.
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