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#1
Posted to rec.woodworking
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Which Foredom: 1/3@15k or 1/6@18k or LowTorque@5k
I'm thinking of buying a Foredom power tools and would like any opinions
on the advantages/disadvantages of their motors. Basically, they have three types of motors: 1) L - high-torque/low-speed motor (no HP rating is given for this model) 2) TX - 1/3 HP with top speed of 15,000 rpm 3) S - 1/6 HP with top speed of 18,000 rpm There seem to be heavy duty versions of the three above, as well. Basically, I see doing just some light carving and polishing-prepping of metals. I used to have a Foredom that I bought in the 1980s and never found myself thinking it lacked power. I have a Dremel now which slows down the second it touches anything. Does anyone know if having 3,000 more RPMs has any advantage? Seems like a 20% speed gain, but may not be noticeable. The high torque/low speed model is said to be perfect for stone-setting, wax carving and other low speed applications demanding precise control. Are the faster ones too powerful? Lastly, I'm probably going to get a handset other than their clunky standard one, I remember thinking the standard one was just too fat to manipulate well with the thumb-fingers. John Poole |
#2
Posted to rec.woodworking
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Which Foredom: 1/3@15k or 1/6@18k or LowTorque@5k
On May 22, 11:11 pm, "John L. Poole" wrote:
I'm thinking of buying a Foredom power tools and would like any opinions on the advantages/disadvantages of their motors. Basically, they have three types of motors: 1) L - high-torque/low-speed motor (no HP rating is given for this model) 2) TX - 1/3 HP with top speed of 15,000 rpm 3) S - 1/6 HP with top speed of 18,000 rpm There seem to be heavy duty versions of the three above, as well. Basically, I see doing just some light carving and polishing-prepping of metals. I used to have a Foredom that I bought in the 1980s and never found myself thinking it lacked power. I have a Dremel now which slows down the second it touches anything. Does anyone know if having 3,000 more RPMs has any advantage? Seems like a 20% speed gain, but may not be noticeable. The high torque/low speed model is said to be perfect for stone-setting, wax carving and other low speed applications demanding precise control. Are the faster ones too powerful? Lastly, I'm probably going to get a handset other than their clunky standard one, I remember thinking the standard one was just too fat to manipulate well with the thumb-fingers. John Poole I like my 1/6HP model and have never needed more power. I have the smaller handset too, but usually use the 44T with a 1/4" chuck for main hogging off wood. Main benefit of having more than one handpiece is to leave different chucks in each and not have to change when going from one shank size to another. It is a lot easier to switch handpieces than it is to change the chucks. I also have a Dremel with shaft, and a super micro-motor tool for detail work. All that- and I don't even like power carving! I like carving birds in tupelo though- and that requires rotary power: http://www.woodworks-by-donna.com/sc...-of-birds.html Donna Menke |
#3
Posted to rec.woodworking
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Which Foredom: 1/3@15k or 1/6@18k or LowTorque@5k
If by "high torque" you mean the motor with the gear reduction
unit on top with the flex shaft coming off it - that'll give you the torque - mechanically that you probably could use - spinning a bur at 6-10K won't speed up how fast it cuts much - and can burn our wood if you push into the "cut" hard. The high torque, low rpms will cut faster - with more control. There is another approach that will give you both higher torque AND the ability to go up to higher rpms. Old Foredom flex shaft set ups used a "carbon pile" variable resistor to control the motor speed - basically bleeding off current before it gets to the motor - think of the old sewing machine foot pedal things. The "solid state" foot controls have a "full wave rectifier" in them that gives you more torque at low rpms where the carbon pile/ sewing machine pedals wouldn't. Think of a sine wave and you're only getting "power" on the "UP" side |
#4
Posted to rec.woodworking
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Which Foredom: 1/3@15k or 1/6@18k or LowTorque@5k
hmm... is there any case for high speeds, e.g. 10,000 to 18,000 rpms?
On reflection, I realize that as the diameter of the tool gets smaller, the RPM must increase to keep the cutting speed constant. It looks like for buffing (and I do metal work at times), having the high RPM for small buffs is needed. A six inch (6") buff running at 1725 rpms will have a surface speed of approximately 2,710 ft./min. Using the formula: Speed (ft/min) RPM = ----------- Circumference (ft) [Pi * Diameter] I solve to: 1725 * (22/7 * 6 * 1/12) =~ 2,710 ft/min To get the same sort of speed on a 1/2" buff, I'll need to calculate the RPM: I solve to: 2,710/(22/7 * 1/2 * 1/12) = 20,700 For a 1/4" buff, the RPM needed would be 41,400! (Wikipedia is our friend: http://en.wikipedia.org/wiki/Cutting_speed) So, I agree that for wood cutting the high RPMs is not desirable. If I want to have buffing capability for a very small diameter buff, then the high RPM becomes desirable. charlieb wrote: If by "high torque" you mean the motor with the gear reduction unit on top with the flex shaft coming off it - that'll give you the torque - mechanically that you probably could use - spinning a bur at 6-10K won't speed up how fast it cuts much - and can burn our wood if you push into the "cut" hard. The high torque, low rpms will cut faster - with more control. There is another approach that will give you both higher torque AND the ability to go up to higher rpms. Old Foredom flex shaft set ups used a "carbon pile" variable resistor to control the motor speed - basically bleeding off current before it gets to the motor - think of the old sewing machine foot pedal things. The "solid state" foot controls have a "full wave rectifier" in them that gives you more torque at low rpms where the carbon pile/ sewing machine pedals wouldn't. Think of a sine wave and you're only getting "power" on the "UP" side . /\ -----/ \--------/-- \ / \/ The rectifier "flips" the "DOWN" side over and makes it "UP". At high rpms the effect isn't noticable. But at low rpms, relative to the old "resistor" foot pedals, you get not quite double the power where you notice the' difference - at low speed. . /\ /\ -----/ \-/ \--- I've had a Foredom for a LONG time - it's only 1 amp so that's less than 1/6th hp - with the SR-1 full wave rectifier foot speed control. I've ground metal with it, wood, plastic and an occassional finger. I'e used it with small dental burs, larger "bone burs", small circular saw blades and recently with one of those reciprocating handpieces yoy insert carving gouges in. NEVER bogged it down. If you're working at chainsaw carving size, you might look into ArborTech's reciprocating attachment for die grinders and hand held disk sanders/grinders. They're in the 1/4 to 1/2 hp range. You'll snap and inserted gouge before you bog one of them down. charlie b |
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