Slow down a drill press ?

[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..........

[sparky961]

... or you just get yourself a mill

They work pretty good as a drill press too ;)

[MetalMuncher]

I have a mini mill. But it's spindle height isn't quite enough to effectively use the tapping head I want to get.

The kit I found online is made by Rogue Fabrication. I think it is what you folks meant by a counter shaft, but part of the kit mounts outside the belt housing in order to get a nice 4:1 reduction. I've emailed them to see if it will fit my drill press.

[sparky961]

Well that's a little ironic.  I'm sure the picture of their 4:1 reduction kit is mounted on a drill press with the same main casting as the one I sold.... that has a mounting hole inside the belt cover for the counter shaft.

My advice: if this is for commercial use to make immediate profit, just buy something that gets you set up immediately.

If this is for hobby use, or for that "future business idea" that may or may not happen, take the time to build each part yourself.  I don't know your skill level, and it really doesn't even matter.  Your desire, coupled with the assistance from the great people that contribute to this forum can make pretty much any project a success.

Don't have the equipment?  Don't let it stop you.  I've seen plenty of wooden pulleys that work just fine and are much quicker/easier to make.

Sorry if I'm getting a bit ranty...   Most of the above is directed as much at myself as it is you.  ;)

[MetalMuncher]

I value all opinions here.....whether I use them or not.   But we each have our own way of viewing things, so I respect that.

Not for a business. If it were, I'd be investing in something serious to get the job done. Just looking for ways to reduce this aggravating wrist tendonitis that is trying to hamper one of my retirement hobbies. I just finished putting a larger table and Y Axis power feed on the mini mill (the latter of which was to avoid so much hand cranking - I've had power on the X axis for some time now). In the process of doing the table upgrade, on my mini mill (SIEG X2 style) that has a column stiffener modification, I had to D&T some holes in steel plate. Although the larger table would be a "bolt on upgrade" as purchased from LMS on a "stock" X2, they made enough changes in the tail end of the casting that it turned out to be a challenge to get my stiffener plate moved over. When I get up into 3/8 taps and larger, even using spiral flute taps now, my wrists don't like it. Been looking at tapping heads for a lot of years, so I decided to get one. All things considered, it will have a lot more room to operate on the drill press, where the original mill table from my mini mill now resides! I wish there were a reasonable way to extend an X2 mill's Z axis. I keep hoping someday someone will make a longer column casting for these mini mills.

Having seen the way Rogue puts these speed reduction kits together, I feel it falls under the category of "it would probably cost me more to buy or make the parts than their kit sells for", and also they have already worked out all the mechanical problems sure to be encountered along the way, and figured out the reduction math. I do enjoy designing and building things. But in this case, if their kit will work for me, I'd buy it. Now, when I am told I can't do something, or that something simply won't work........well, that's when the desire to engineer a solution goes into overdrive. 

Speaking of ironic - I don't know what brand that red drill press in Rogue's photos is, but it looks VERY much like my Craftsman 5 speed 13 Inch model in the way it is constructed.

Did you look at their 16:1 reduction kit? Rube Goldberg would be proud of it! lol

[MetalMuncher]

I just ran across an old forum thread where a fellow used parts made for a 12 speed Grizzly drill press to slow his old restored Atlas drill press down. Specifically, the center shaft, bearings, and center pulley, and snap rings from the Grizzly model. Although the forum thread is 9 years old, that model Grizzly is still sold, so the parts are still listed.

But if I wanted to try this, which would be nicely contained within the stock belt cover, I would need to invert the stepped pulley on the motor. And, that can't be done with the current pulley. The motor shaft doesn't extend up through the entire pulley, and the setscrew is down at the small end of the stack. I would need to swap the motor pulley with a stacked pulley that has a drive bore running the full thickness of the whole stack of 5 pulleys. That way it could be inverted as required.

The down side is he only got 2.2:1 reduction. I'd like to get the 4:1 reduction offered by Rogue's kit.

[trevoratxtal]

A "Drill speed reducer" fits in the chuck and turns only when grasped.
So fits in any drill Press or portable.
Very useful for tapping .
A Ebay search will give a clue.
I have used one for many years. works well.
Trev.

[mattinker]

I know you've made enquiries about the "Rouge" reducer kit, but I very much doubt that it would be cheaper to buy than to make!

Here's one of those nice old articles on doing it!

[MetalMuncher]

I know you've made enquiries about the "Rouge" reducer kit, but I very much doubt that it would be cheaper to buy than to make!

Here's one of those nice old articles on doing it!

Thank you! Actually, the last 3 parts on the list in that article, in prices I am seeing today, come within $20 of the 4:1 Rogue kit I am considering, which would take my press down to 100 rpm. The article doesn't seem to mention the reduction ratio achieved. The other thing about the method in that article is that the motor, being inverted, has to be reversed. I know not all motors have that feature, and I would be surprised if Craftsman used a reversible motor on this press in 1985, when corporations were looking hard to cut their costs. Back when that article was written perhaps reversible motors were more common. I do know the motor has a centrifugal contact assembly because of the capacitor start. I've had some issues with it in the past. Not sure if that would work in reverse rotation?

Having sent the user manual PDF for my press to Rogue, they have responded that although Craftsman on rates its motor as 1/3HP, it is on a frame which is common for today's 1/2HP motors, and is probably under-rated. So the motor bolt pattern should match, and they think their kit will likely fit my drill press.

One road block I did discover last night - if I have to invert the 5 speed cone pulley on my motor (likely for anything I would want to try which stayed contained at the top of the press) the best price I found on a pulley alone is $80, and they are not easy to find. Also, the motor shaft is too short to allow an inverted cone pulley unless its bore and set screw reached all the way out to the very end of the large diameter pulley in the stack. I could not find any that were made that way. To sidestep all these hassles, the Rogue kit seems like the preferred choice.

[MetalMuncher]

A "Drill speed reducer" fits in the chuck and turns only when grasped.
So fits in any drill Press or portable.
Very useful for tapping .
A Ebay search will give a clue.
I have used one for many years. works well.
Trev.

Thank you! An interesting tool I did not know was out there. Looks like they were made for portable drills, back before variable speed drills came on the market.

[mattinker]

Just a thought, you have to reverse the motor if you turn it up side down. If you put the big pulley on top of the jackshaft just above the cone pulley, the motor can be mounted the same way up as standard.

Regards, Matthew.

[MetalMuncher]

Thanks! I had not considered that.

Since it appears the Rogue Fab. 4:1 kit works for me, I have ordered one to try.

Thank you all for the input. There is much to consider when thinking of devising such a device, which is one reason I went with the retail choice. If they had been charging double their prices, I would probably have built something on my own. But for the cost of the parts in these alternatives, it wasn't much more cost to try their tried and true kit.