Official Luthiers Forum!

Hi all,

I just bought an older General 13" wide belt sander. It is open ended so can do up to 26". Anyway, it looks as though the feed belt rate is fixed and fairly slow. Is there a way to remove the feed belt switch and add something that will increase the feed rate? Alternatively, is putting on a variable feed rate motor much of a chore and if not and I need one where can I get one? Here are the pictures:

Here is the feed motor:



This is another shot of the diagram on the feed motor:



Here is the switch box. The toggle switch on the bottom turns the feed roller off and on:



And here is a shot inside the switch box:



Any help/advice is much appreciated!

Thanks

Shane

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Canada

Shane, just from the label on the motor, I'd say there's no way to increase the motor speed. It's a synchronous AC motor. To do what you want, you need to replace the motor with a DC type that you can put a PWM speed controller on. Alternatively, you could speed up the belt by making the pulley/gear (or whatever is between the motor output shaft and the feed belt mechanism) larger, but that might be a mechanical nightmare.

HTH,
Dave F.

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Cambrian Guitars

"There goes Mister Tic-Tac out the back with some bric-brac from the knick-knack rack"

Thanks Dave, I just received the manual for the sander for our regional General Rep and the manual says that it is an AC motor that is gear reduced to just under 4 fpm. So I might try and find away to retro a DC or I guess I could also change the gears and try for like 16 fpm and the use a router speed controller to reduce as needed. I am not sure if that would be easy or even work. I will look some more!

Thanks again

Shane

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Canada

Shane,
A few years ago I build a motorized dish sander using an AC three phase motor and then purchased a VFD (variable frequency drive) to convert single phase to three phase. This allowed me to have total control over speed. I believe I picked up the motor and VFD both new but surplus for probably not much over $100 for both. The VFD was from EBay and the motor was purchased local. Just a thought.

Nice job getting the wide belt. I purchased an older one last year and the work great.

Good luck!
Brad

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Brad
Avon, OH

Shane,
On a side note, i tried setting up a gen machine like that and discovered that the drum was crowned & never could get it to thickness evenly across the width of the board. Have you checked that yet. I ended up buying their 13" closed. But the "byrd" head on my thicknesser is where it's at now.
MM

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Mike McNerney

A 3-phase motor with VFD would probably be the most economical & easy route.

3-Phase motors are abundant on Ebay & in the industrial surplus world. 3-Phase motors are also much more reliable and last longer than single phase motors.

Personally I wouldn't get a used VFD. I've bought 4 VFD's from http://www.factorymation.com/ & have been very happy with their service. They have competent tech support who can help you with any questions before & after the sale. If you go to their site they have them categorized as "AC Drives".

Kevin Looker

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I'm not a luthier.
I'm just a guy who builds guitars in his basement.
It's better than playing golf.

I would like to see manufacturers of wood working tools offer an option of VFD motor control. Variable speed and reversing along with soft start and braking are very useful in some applications.

So, I took the unit apart a bit (not entirely) and had a look. The motor has spiral splines that fit into the gear reduction. I didn't pull the reducing gear box off the end of the feed roller shaft so I don't know how that looks. I read through Brad's old rim sander post and he stated that he can exceed the motors rated rpm with a vfd and a 3 phase motor. So right now the AC motor spins at 1750 and is geared to about 4 fpm. So could I get a 3500 rpm 3 phase motor and increase that speed to 150% giving me a range up to about from 0 to 12 fpm?

Thanks
Shane

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Canada

No you don't want a 3 phase motor. That would require 440 volts. You want a 110 variable speed motor. One from a different sander might work if General does not have one that will plug right in, like the Jet or perhaps you could get a cheap one at harbor freight.

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http://goatrockukulele.com

Most 3-phase motors come in dual voltage - not only 440V.

Look at the plate on the motor & it will tell you.

You can also double the rated speed of the motor. Look at the frequency adjustment of the VFD. In the US, motors are rated at 60 Hz. If the VFD can produce 120 Hz (as most can) the speed will double.

Kevin Looker

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I'm not a luthier.
I'm just a guy who builds guitars in his basement.
It's better than playing golf.

Thanks Kevin,

I am aware that there are LOT of 220 volt 3 phase motors (a quick look at ebay shows that). I will try this machine as is for a while and then consider looking for a 3 ph motor that is similiarily equipped with a spiral shaft and go from there. That might be a hard one though so maybe I will have to re do the entire drive process.

Thanks again for all of the assistance!

Shane

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Canada