# Drill Press Speed Reducer



## old toolmaker (Jul 6, 2016)

Are there any plans around for building a drill press speed reducer?
I have a restored Toro drill press with a low end RPM of 860.  I would like to reduce the low end speed to around 250-300 RPM.  I think I can build a jack shaft (lay shaft) that will fit into the top end of the tubular column and it would carry the stock four step pulley as well as a large pulley driven from a smaller pulley on the motor.

Dick


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## 47convertible (Jul 7, 2016)

Dick, are you thinking of something like the 3 pulley system on this Jet 20" DP? It allows speeds of 150 to 4200 rpm with belt changes. The middle pulley has a shaft that mounts in an oillite bronze bushing set in the cast head (if I'm remembering correctly)  and then there is an arm that goes out maybe 3 inches to a post that mounts the pulley. This allows the middle pulley  to swing for belt tensioning. The shaft and bushing are offset from the plane of the two end pulleys by the length of the middle shaft arm. It was recently sold so I have to rely on the one photo I have. 

On my 17 inch Jet I went to a variable speed 1.5 hp DC motor but retained the motor, center and  spindle pulleys as you can see in the other photo. This gives almost an infinite number of speeds. The DC motor and controller were from a donated treadmill. I got lucky on that as some treadmill motors are what are referred to as 'beer can' motors and not worth the effort to salvage. More expensive treadmills have higher quality and usually more powerful motors and drives. The downside of varying the electric motor rpm is that it uses less current which means lower power (torque). The  upside is that most drilling I do is 3/8 and smaller. I can slow it down enough to power tap from the chuck....once I figure out the wiring of a dpdt switch to reverse the motor.
Jerry


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## Karl_T (Jul 7, 2016)

switching to a 3 phase motor and VFD is one excellent way to do it.


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## Randall Marx (Jul 7, 2016)

Hi Dick and welcome to the forum!
I've been considering something similar for my 1980'2 model Enco drill press. Mine is a PD13, which I believe means it is about a 13-inch swing and is currently set up with 2 pulleys (4-6 steps each, cannot remember for sure right now). I need it to turn slower for some of my planned projects. The current plan is to implement something like Jerry described and gave pictures of. If you get to this project before me, please let us know how it goes and if you run into any issues. I'll do the same when I get into it.


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## brino (Jul 7, 2016)

Hi Dick,

Welcome to the group!

There were also some useful ideas posted in this thread:
http://www.hobby-machinist.com/threads/gearing-down-a-jet-drill.42251/

-brino


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## Silverbullet (Jul 7, 2016)

This is a great forum . Welcome to you ,I'm going to add a Jack shaft to my 20" Rockwell delta . I think all drill presses run to fast at there lowest speed. I'd say a low of 60 or 80 rpms would be the starting range and 2500 to 3000 as top would be best , just my preference . As I said welcome.


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## ndnchf (Nov 3, 2016)

About 5 years ago I restored my WT-900 drill press.  I debated the options for variable speeds and decided to go with a 220v 3phase, 3/4hp motor controlled by a 110v input VFD.  At lower speeds with a VFD you lose some power, but the 3/4hp motor was a step up and works just fine.  After 5 years of use I couldn't be happier with it.


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## Chayse (Jan 20, 2017)

I have an old Atlas Model 52 that I picked up off CL....since it was manufactured for drilling wood, I browsed the bay for the factory reducer, since I would be mainly using it to drill metal. So, to no avail, i made my own.

I used a muffler expander to lock my reducer into the factory support, then fashioned up a pulley system using some oilite bushings and pulleys. I do not know if this would work on your DP but it definitely made my life easier. Total cost was roughly $40....bushings and pulleys and miscellaneous hardware. The plates are 1/4" aluminum I had left from a welding job. I can chuck up a 3/4" drill bit and drill 1/4" plate with ease....I would say at roughly 50-60 rpm...a nice steady ribbon off the bit. Nice thing is, the attachment can be removed in a matter of minutes and returned to factory speed setting should I need it.

I can post more detailed pictures if need be....


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## brino (Jan 20, 2017)

Chayse said:


> I used a muffler expander to lock my reducer into the factory support



Excellent re-purposing!
Nice mod all around.

Just be careful around the open belts.

-brino


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## Dunc1 (Nov 25, 2017)

Here's a few more ideas from old magazines. Google the Popular Science & Mechanics references. All the old issues are online.
http://www.opensourcemachinetools.org/archive-manuals/large-hole-drilling.pdf
Pop Sci, Nov 65
Pop Mech, Mar 42
If you have access to the magazines Home Shop Machinist/Machinist's Workshop there are likely several ideas as well tho I don't have any specific references.
I vaguely recall a photo of a drill press with a geared reduction box added to the mix. Given the reduction ratio on many of them I expect the lowest speed would be in the vicinity of "revolutions per hour".
I used the opensource technique above and was able to drill 1" holes in mild steel with it using lots of cutting fluid & patience. If you are using >1/2 inch drills (Silver & Deming) it is a really good idea - based on my experience - to purchase the ones with the three-flats on the shank to prevent slippage in the drill chuck.


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## GarageGuy (Nov 26, 2017)

I made one for my Delta DP-600 for the same reason.  Lowest speed was 800 RPM, now it's 283 RPM.  I fitted a steel slug into the open column for an intermediate pulley on a ball bearing shaft.  It pulls right out and can be switched back to original in just a few minutes.

GG


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## u50067 (Jan 6, 2022)

In addition to the jack shaft pulley, I replaced the 1725 RPM motor with an 825 RPM motor.  This reduced the spindle RPM to approx 135 RPM.  I think the 825 motor was a direct drive fan motor.  Am not sure but believe the fan motors on the outdoor AC units are slower speed motors and would likely be 230v motors.   So check the RPMs of motors at sales, etc. I picked mine up at a pawn shop and have another approx 820 RPM 230v motor I found at an auction.


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## jmarkwolf (Feb 19, 2022)

I've got a similar setup to Garage Guy on my 1956 Delta 15in drill press (pics below), that I inherited from my dad. Originally, I thought it was something he had fabricated to fit the top end of the column, because I'd never seen another on this model drill press. But I recently saw pictures of a nearly identical setup on a Missouri barn find drill press of the same make/model as mine.

Perhaps it was a kit, or someone published plans.

It's been working great on my drill press for many decades. I've never checked the speed ranges. I'll have to make a point of doing that once I get it all back together after the refurb.

But a 3-phase motor and VFD like Karl says would be a tempting solution.


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## rwm (Feb 19, 2022)

Industrial sewing machine motor and controller:


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## HarryJM (Feb 22, 2022)

1955 Delta 17-210 drill press/DP-600 drill press with a Delta 1 HP 3 phase motor and a KBMA-24D VFD for 1 phase 220 in and 3 phase 220 out.


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## brino (Feb 22, 2022)

HarryJM said:


> 1955 Delta 17-210 drill press/DP-600 drill press with a Delta 1 HP 3 phase motor and a KBMA-24D VFD for 1 phase 220 in and 3 phase 220 out.



........and with the only holes in the table looking like symmetric vise mounting holes; NOT the usual "arc of shame"!
Nice!

Brian


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