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Slowing Down My Drill Press !!!

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chip maker

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I have a bench top drill press that only has 5 speeds 700-3000 Rpm. What I would like to do is add an idler in the center to be able to slow down the rpm. Looking at manuels for like 12 speed presses and they just seem to have this center idler and 2 belts instead of one. My guestion is has anyone else done this and did it work out alright? I looked under the cover and there is a possible mounting for the idler so I'm not sure if it is worth the time to try and set this up or not. Using this drill for wood work wasn't a problem but now doing a lot more metal work also I need to slow it down to help save on the bits. Thanks
 

george wilson

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I bought the center pulley "Hi-Lo speed attachment for my 1963 Craftsman drill press when I bought it new. It just has a round piece of cast iron that goes down into the top of the column about 2". The pulley has a ball bearing in it's center. The pulley's axle is held off center in the cast iron plug,so the pulley can be rotated to tighten the front belt. The rear belt is tightened by the swinging motor mount(not the most powerful arrangement,but the motor is only 1/2 H.P..)You will probably have to make these parts,but they are do able. There is a set screw on the plug that can be tightened to jam it inside the column,but I never use it. My drill press can go from crawling speed to 10,000 RPM with the center pulley. You need VERY low speeds for drilling larger holes in steel. I think mine does about 170 RPM. But,in reality,the motor is not powerful enough to drill holes much larger than 1/2". For that,I also have an old 20" Walker Turner drill press with a VFD on it.

Most modern larger drill presses will only go down to 300 RPM,which is way too fast for drilling larger holes in steel. So,their rating of drilling ,say,1 1/4" holes is a joke. If they have powerful motors,and are 3 phase,a VFD can effectively slow them down.

Most modern larger lathes go too fast too. I did have a 19" swing lathe at work that would go 11 RPM,which was VERY useful,especially for large diameter cast iron work. Cast iron easily blunts tools if turned too fast,most especially HSS. Carbide is needed,but so is SLOW SPEED. My 16" lathe at home does 60 RPM,way too fast. It swings 24" in the gap. I made a special pulley to slow it to 1/2 speed,but even that is not slow enough. Fortunately,most of my work is not large. I am at least able to face off my large cast iron face plate(they always need a bit of truing up when new). My lathe is single phase,so I can't put a VFD on it. When I bought it,they were not yet common.
 

Rbeckett

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That was a way we tested applicants for our shop. Hand them a hand drill and a 1/2 inch drill bit and see how they used the trigger to keep the speed as low as they could. If they just chucked up the bit ad fell on it wide open we took a pass on hiring them because it was obvious they were not what they claimed to be. Ahhh, the good old days when PC meant a printed circuit not politically correct...

Bob
 

chip maker

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George,
So you do have a center pulley on your drill press, is that pulley the same dia. as the other two pulleys ? Buy the photos some of the other machines I seen seem to have the same size is the correct? If it is a different size can you give me the sizes of yours so I can figure out the size difference to mine. Thanks for the info.
 

george wilson

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Yes,the center pulley is about the same size. You do need to be careful about the diameters,or you will be finding that shifting the belt will require more pulley travel,or more motor travel than you can get from the drill press. You only have a limited amount of travel available.

The above site reference is excellent. That is the drill press I have,but it is a few years older. Mine is "smoke gray". Glad I didn't get the gold version! It has been so long,I was rather guessing at my speeds.
 

george wilson

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Parts cheap??? That's the first time I ever heard of getting parts cheap! Usually,if you had a $3000.00 lathe,it seems that you could buy a new Rolls Royce for the cost of buying enough parts to build another from parts!!:)

I also think you should buy the Grizzly parts. You might have to make a column plug to get that crank shaped swinging arm ( 063) to fit. But,it would definitely be a LOT easier to just buy the parts.

That setup has a LOT more movement ability than my old craftsman setup.

I'm glad to know about them,too,should I ever(not likely) want to modify another drill press.
 

chip maker

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Tmarks11, The Grizzly is the one I looked at to get the idea to do this conversion. You are right, the cost of the parts isn't that bad. I didn't look at the prices for the parts when I first looked up the configuration. Even with adding the cost of the belts I couldn't make the hard parts for the same money. The cost of the material for the pulley alone would cost more. Thanks for the push in that direction and I think I'll order the parts today. Thanks again.
 

chip maker

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Just wanted to let all that helped I just got done ordering the parts from Grizzly. With adding the two belts and shipping total came to $63.00. When I get into changing this over I will keep you posted as to how it works out. Thanks again guys for all the input.
 

extropic

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I came late to your thread so I couldn't help, but think you did the right (easy, good enough) thing buying the grizzly parts.
 

chip maker

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Just writing to let everyone know how this update to my drill press worked out. The parts came from Grizzly and I started the upgrade today. Needless to say, and I knew this upfront things didn't just fall together. The idler pulley mount was larger than the hole on my drill press so had to drill the hole and also use some shim stock because I only had a 9/16 drill and needed one just a bit smaller. Tried to figure out how to set this up on my lathe to just turn the shaft down but couldn't get it to fit. Next the motor pulley needed to be flipped over and then the set screw would not be even close to tightening the pulley to the shaft. This pulley is not solid so I made a plug that fit in the under side to give me extra material to thread in a new set screw and also give more support on the shaft. Than came the belts, sorry but they don't fit, they are both to long for my housing the Grizzly machine must be longer in the upper housing. Off to Advance Auto and was lucky because they had belts that would work for me. After all this it has worked out GREAT and I can't be more satisfied with the out come. I went from a 5 speed to a 12 speed and the lower speeds will be worth it. In all, even with the not used and replaced belts I still only have about $70.00 in this upgrade. IMG_0001 Large Web view.jpg IMG_0002 Large Web view.jpg IMG_0003 Large Web view.jpg IMG_0004 Large Web view.jpg
 

francist

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Yup, there's always the collateral parts you didn't think of to make it all come together. Glad it worked out, what did you end up with for a bottom-end speed now?

-frank
 

itsme_Bernie

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Great job, and great sourcing... I am also curious as Frank asked!

George, we obviously have similar tastes in drill presses!

Bernie


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chip maker

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To be honest I haven't checked it with any type of meter or anything but I did buy the belt adjustment label also from Grizzly and they show the slowest speed at 140 and than 260,320,380,480,540,980,1160,1510,1650,2180 and 3050. Before the redo the press started at 700-3000. I always thought that it was really to fast but never thought of trying to slow it down. This has been another great upgrade to another tool that I have had for many years already and just used as it was till now. Thanks John
 

itsme_Bernie

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Fantastic! I am sure it is a huge difference! That changes the usefulness of your machine for metal greatly!

Bernie


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george wilson

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An excellent job,bernie! Very glad that the Grizzly parts were good for the mod to your drill press. It will make your machine so much more useful than it was.

I use the high speed of my drill press to rout out inlays for guitar fingerboards with 1/16" router bits. It is so much better than trying to use a Dremel with the router base,which is what most builders have to resort to. You can see what you're doing so much better.

I can get rid of most of the wood,then use small chisels to get into corners,etc..
 

george wilson

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I have no doubt that cast pulleys can explode. Fortunately,mine hasn't. The shape of my drill presses' casting does cover the spindle pulley enough to keep fragments away from the operator. I don't use the very highest speed on my drillpress. It gets pretty loud and dangerous sounding when at full speed. I use one notch below that!
 

RWL

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It gets pretty loud and dangerous sounding when at full speed. I use one notch below that!
That describes how mine was too. I never intentionally used the higher speeds because there was more vibration than I liked and it just didn't sound right. On the day of the incident I had inadvertently changed the belts to the highest speed. I had even made a belt chart with associated speeds so it shouldn't have been set that high. I knew as soon as I heard the motor laboring to come up to speed that I had chosen the wrong arrangement. The pulley exploded before I could reach for the off switch. Again, thank heaven for the metal guard. Fortunately a member of another machinist forum that I was on then had a Rockwell drill press he was parting out and I was able to replace the 40+ year old pulley. It worked well until I sold it a few years later when I got a 20" drill press.
 

Dunc1

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Found a couple in old magazines (Google gets them):
Popular Mechanics, March 1942 "Removable Speed-Reducing Unit for Drill Press"
Popular Science, November 1965 "Drill-press drive gives wide speed selection"

The last one I have used successfully. I prefer it since you get serious speed reduction from the get-go.
I was able to drill several 1 inch diameter holes in 3/8 inch mild steel plate. For large holes get a drill
bit with flats ground on the shank; otherwise, you will only be "drilling" your chuck due to bit slippage!
I have no other info (aside from the .pdf).
 

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chip maker

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Found a couple in old magazines (Google gets them):
Popular Mechanics, March 1942 "Removable Speed-Reducing Unit for Drill Press"
Popular Science, November 1965 "Drill-press drive gives wide speed selection"

The last one I have used successfully. I prefer it since you get serious speed reduction from the get-go.
I was able to drill several 1 inch diameter holes in 3/8 inch mild steel plate. For large holes get a drill
bit with flats ground on the shank; otherwise, you will only be "drilling" your chuck due to bit slippage!
I have no other info (aside from the .pdf).

After looking at that pdf. that is what the update I did to my drill press accomplished as well. The only thing in that old photo is that they added the other pulley to a new arbor assy. After looking the newer setup does the same thing only a bit easier. it's really neat to see how even back than guys had many of the ideas that we come up with but just solved them in a different way with the means they had at that time. Guess they were also trying to save money but wanted to get a job done.
 

mrbreezeet1

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OP, part #63, where it goes into the hole in the drill press, and pivots for tension adjustment, does it just go into a hole, or did you use some type of bushing or bearing?

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ndnchf

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This is an old post, but i'm curious about the diameter of the plug that goes into the hole. I have an ancient power hacksaw that someone converted to electric, but the motor is too fast. I'm wondering if I could use these parts to reduce the speed. Also, what thickness is the belt - 3/8" or 1/2"? Thanks.
 

mrbreezeet1

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here is my version.
I got the pulley from e bay a while back.
was going to wait til,l I got the belts,to show it,
But you can still tell everything, just needs the belts.
The slug goes into the post, and there is a step on the slug, that bottoms on the top of the post.
The slug is drilled off center to better center the pulley.

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mrbreezeet1

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This is an old post, but i'm curious about the diameter of the plug that goes into the hole. I have an ancient power hacksaw that someone converted to electric, but the motor is too fast. I'm wondering if I could use these parts to reduce the speed. Also, what thickness is the belt - 3/8" or 1/2"? Thanks.
I don't really think it's ideal.
I don't know what your set up and stand looks like, but I'd probably get 2 pillow blocks and some 5/8" drill rod, and about a 3" pulley at the motor, to about a 10" pulley at the one end of the jack shaft, with another 3" pulley at the other end of the jack shaft, to another 10" or larger at the Hacksaw.

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Johnnybar

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This is an old post, but i'm curious about the diameter of the plug that goes into the hole. I have an ancient power hacksaw that someone converted to electric, but the motor is too fast. I'm wondering if I could use these parts to reduce the speed. Also, what thickness is the belt - 3/8" or 1/2"? Thanks.
Do you have a 1750 rpm motor currently?
 

ndnchf

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I don't really think it's ideal.
I don't know what your set up and stand looks like, but I'd probably get 2 pillow blocks and some 5/8" drill rod, and about a 3" pulley at the motor, to about a 10" pulley at the one end of the jack shaft, with another 3" pulley at the other end of the jack shaft, to another 10" or larger at the Hacksaw.

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I've considered a jackshaft set up, but space is limited the way the motor was added. I'd have to make major changes to make it work. The DP reducer is a more compact version of it, but it may not be robust enough. It currently has a 1750 rpm motor. Probably the best route would be to use a gearmotor to bring rpm down to around 700-800 rpm. I don't mean to hijack this thread, but here's a photo of what I'm dealing with.

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LsSix

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You might fabricate a sturdy bracket to be sandwiched between the motor bracket and its mounting point that would hold a 2 sheve pulley to the right of the motor (in your pic above) and get your reduction that way. It would keep the mechanicals out of the way without crowding everything near the flatbelt pulley. Use a screw to manually tension everything.

Personally I would also make up a table to go over the motor and pullies to support the back of the work and protect you and the mechanism while working.

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