I have a Delta Shopmaster Drill press. I would like to reduce the speed
from 610 min to about 300 min rpm. Since this is basically an entry
level model my options are limited. I am not concerned about the
longevity of the motor.
Can a variostat be safely used to reduce speed?
This modification would prolong the need to upgrade models. The reason
I need a slower speed is to run a circle cutting tool from general to
cut neoprene gasket material. 500 rpm is max speed for this tool.
Using a Variac to reduce voltage/speed will cause the motor to overheat
rather quickly. Optional methods would be to change a pulley, mount another
motor externally and use the existing motor pulley as the intermediate
pulley to double-step reduction, change the motor to DC and use the Variac
(with a bridge rectifier) to adjust speed or finally go to a three phase
motor and a VFD. Temporarily mounting another motor shouldn't be too bad a
method, especially if you already have something useable.
I realize this is not responsive to your question but.....IMNO circle
cutters are very highly overated. I doubt you will have much luck cutting
neoprene with one anyways. How about finding something the correct diameter
and sharpening it enough to turn it into a crude die cutter. I have done
this using tin cans, tube and pipe. The only way to control the speed of an
induction motor is with a frequency changer.
Thanks for everyones help.
I knew a variostat would be abusive to the motor, but if I am only
making 25 at a time and then taking it off, I think it is livable. By
the time I modify the DP I already overspent the initial cost easily
with the possiblity of now liking the modifications. I think for
another hundred I can buy a new one that does the job already.
I already made a jig to cut the neoprene sheeting that I am satisfied
with. I would not use this tool to cut more than 1/8" deep. I wood
definately agree more than this thickness a punch would be better, but
I would need two of them custom made for the tolerances I want.
I tried using a linoleum knife around a wood template but it ended up
looking like a item made in a garage.
Circle cutter is not a great tool after using it a while. To cut gasket
material I used a leather punch set to cut bolt holes and circle
cuttuer only to trace a line around abouth 1/32nd deep. I then use
surgical scissors to finish the cut.
I fully agree the way this cutter was shipped is not great for delicate
cuts at all. I would much rather have a 6" punch to do the hole job.
What I would do is find a very similar delta model that has a variable
speed motor control. Then get a schematic to see how its wired in, then
mimic that on your setup. In all likely hood its the same motor. If
its not the same motor you will likely see it in the schematic.
"Then said I, Wisdom [is] better than strength: nevertheless the poor
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