1/4HP bench drill modification-slow speed

Hi folks

Not long ago, someone from Denmark googled me to ask how I made my 1/4 HP bench drill to go slow speed. Hence, I would like to share my design with anyone out there facing the same problem. Normally the bench drill of this type has a minimum speed of 500 rpm, not suitable for drill bits ranging from 7mm to 10mm. My design allows the spindle speed to go as low as 150rpm or lower with high torque output.

Moreover, some other added stuff to improve the press srill further

See album > Steve's Workshop

Any doubts, do drop me a note, glad to learn and share ideas.

Regards,

Steve Wan

A decent low speed high torque system makes a huge difference for drilling and milling larger holes

With a stiff enough system you can even mill aluminium with no lubrication because of the lack of heat a slow speed generates

Nice to see you making your own solutions

Hi Ady

Thanks! Yup! I heard a lot about small drill press not slow enough for bigger drill bits so I have put up a solution here to share. In fact, the design worked so well that I got another same brand and model drill press as spare after a period of 5 years.

As things go, China stuff may change as well as prices.

Steve Wan

Steve, would you be able to put a grove at the top of the motor spindle, adjacent to the top center pully, or any of the other center pullies? If so you would need another belt to fit, but there would be a further reduction in speed. Ian S C

Hi Steve,

Not being familiar with your particular extra small drill press, what was changed?

Was it just the belt run you changed, or did you also make a smaller motor pulley?

Did you add a fifth position to the middle and spindle cone pulleys?

Your other mods to the drill press ie the work stop, rack and pinion, and table support look well done. Nice job.

Thanks JD

Last week I had the pleasure of visiting Steve's workshop, full of economically innovative machine tool improvements and accessories.

Very high level of craftsman ship, many larger parts are fashioned entirely with hand tools requiring much patients.

Steve, thanks for an interesting and informative visit. I am looking forward to seeing the Aciera progress over the coming months.

Nigel

High Steve,

Very nice mods but I'm not quite sure what your last picture shows when you say High speed for drills smaller than 6mm. A small pulley driving a large one as in your picture will reduce the speed. Surely it would be faster if the intermediate pulley was used so that you can have a large pulley driving a smaller one on the quill, thereby increasing the speed?

At the moment you appear to have about a 4 to1 reduction from motor drive shaft to drive pulley which would give a speed of about 350 rpm (assuming a 1400 rpm motor), a bit slow for very small drills. For example in Mild Steel recommended drill speeds are approx 750 rpm for a 6mm drill and 3000 rpm for a 1.5mm drill and double that speed in brass.

Terry

Hi Ian SC

I see your idea by making a new groove at the motor pulley top would definately slow the speed more.

But as you know the pulley at the middle are resting on a flat steel plate and not a made rod support like those medium range drill press which may tilt the pulley side way so I decided to belt only the lowest grooves instead.

Hi Jeff Dayman

If you own a press drill at 1/4 HP you can note the difference. It comes with 2 pulleys with 5 steps and the lowest speed is at 500rpm. I turned the small cap pulley and shifted the original motor pulley to the middle. The table support has 2 adjustable heights to add more drilling space when the moveable drill table is too low. Simply swing the moveable table back and use the support table.

Hi Nigel

By far you're the 1st UK visitor to my small homeworkshop A pleasure to share with you my past and new hobby from AirFix, Revell, Tamiya to Sherline metal-machining. Wish you ever success in your new year resolution.

Hi Terry

Yes! I know about that I decided to narrow down my speed to 2 ways. High and low. The high speed is best for 4mm and low speed for 8mm. Those near the range can yet be used. I have tried drilling 1.5mm using the high speed although slow but gets the job done without breakage.

Thanks for your output guys, I would try to share more in the near future than asking questions.

I am very satisfied that other hobbyists also notice the need for low RPM bench drill. Four years ago I really needed to use very low RPM on my cheap Chinese bench drill, and I attached to its back an inexpensive hand drill with rubber round belt, which used the original motor with its pulley as a "middle" pulley. Of course, the bench drill was not plugged in. The hand drill was powered through electronic regulator originally sold for controlling routers. I was even able to change the direction of rotation, useful for tapping. I have one picture of this setting in my computer, but - being a new member - I do not know how to post it. Cheers, Andrzej