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Slow down a drill press ?

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MetalMuncher:
I have a floor model Craftsman 13 inch 5 speed drill press which uses a pair of multi size pulleys and belt drive. I never find the need to use its highest two speeds. It's lowest speed is 400 RPM. I would like to find an affordable way to reduce its speed further, so when I get a tapping head I will be able to use a speed range of 70-200 RPM (called for on some calculation charts for tapping certain materials at certain sizes with a tapping head).

Is there an affordable way to reduce the speed of this press?

velocette:
Hi
Probably the easier solution would be to fit a counter shaft  on the motor bracket and fabricate a bracket for the motor that mounts the motor with the drive shaft and pulleys to drive on to the bottom of the counter shaft .
Poly Vee belt pulleys are easy to fabricate from cast iron or aluminium.
You could go nuts and make the drive to the counter shaft multi speed.

Eric

sparky961:
A few possibilities crossed my mind when I saw this:
- Reduce the speed through the use of a counter shaft (per Eric's more detailed description)
- Change the pulleys to a more acceptable ratio if there's space and you can fabricate or purchase them
- Run the motor with a VFD for speed control .... not too familiar with the details, whether it will work with capacitor start motors, etc..  Could be the easiest turn-key solution if it works.  Even if you had to put a small 3-phase motor on there the cost may offset the time you spend dicking around with it.  Drill presses with low speeds for metal working seem to be somewhat rare to purchase at a reasonable price so it may be worth the trouble.

I recently sold a drill press I refurbished.  It had 5 or 6 speeds but also had another hole in the casting for a third pulley to increase the number of possible combinations.  This was inside the belt cover, which may be easier than messing around at the back where the motor mounts.... again, if there's enough room.

Oh, and the final option is to only drill small holes with it. :)

MetalMuncher:
I appreciate the input! Thanks!

The internal counter shaft reference may be what I am about to investigate further online. I searched for reduce drill press speed while in a waiting room today for an appt., and quickly found at least one company making speed reduction kits for drill presses. Haven't had time to dig deeper yet.

I don't think we have 3-phase power here. I live in a rural area. Going toward that route, or a VFD, would probably be too expensive. But if there is a way to fit a pulley oriented speed reduction under the belt cover, that seems ideal. They claim to have a video of a cheap-o drill press drilling a 1" hole in a steel plate, using their kit. I'll post more when I see the video.

As far as "drill small holes", this drill can run a 3/4" Silver/Demming in steel very nicely. It just won't go below 400 rpm, which is what I am after. Ideally 70 rpm would be good. At that speed I could run a tapping head on pretty much any kind of metal, according to the charts.

IMHO, most affordable drill presses have 2 major shortcomings. They don't go slow enough, and their quill travel is about 1/2 what it should be. Why can't a fellow drill, and tap or ream a hole in successive operations on one spot without having to crank the table (losing location in the process)? Drill presses need at least a 7" quill travel to do that, due to the length of drill bits, a tap handle with a tap in it, or chucking reamers. I use an extra chuck on a jack shaft for the jobber length drill bit to bypass this issue, but I have to index mark it to the exact same rotation on the drill press chuck each time I use it, or the TIR gets unacceptable. Of course, one COULD put a DRO on their drill press.......... :D

sparky961:
... or you just get yourself a mill

They work pretty good as a drill press too ;)

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