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20" Production Drill Press

January Project of the Month [3]
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maker of things

H-M Supporter-Premium Member
Jul 23, 2014
More of a overview than review of the Central Machinery 20" Production drill press. #39955 and #61484. Luckily I got a 61484 as it has a MT4 spindle instead of MT3 on the 39955. Same as my lathe tailstock.
It's good to have a friend to help lift the heavy pieces.

The head is split to permit adjusting the quill. Cover does not have to be removed to do this, I just wanted to see what it looked like.

I popped the arbor out and removed the belts. I did not get even .001" of movement through a full rotation by hand of the spindle.

The provided arbor tir was .002"

With the provided chuck installed the outside of the body measured .003" tir

A 1/2" dowel chucked up ran out about .006" 1" down from the end of the chuck.

Then I chucked up a length of 3/4" ground drill rod

I zeroed out the indicator and plunged the quill it's full travel and read a little over .005" deviation front to back

And again about .005 sided to side

At full extension I zeroed the indicator and again rotated by hand. I measured .01" TIR at nearly 10" from the chuck.

I forgot to check the table to spindle while I had the drill rod in and just grabbed a chunk of 5/8 1018 crs and a Starrett 6" square.
Front to back:

and side to side

So that's the conclusion of the technical section. Next up, fit and finish.
Last edited:

maker of things

H-M Supporter-Premium Member
Jul 23, 2014
So based on the fact that the important part of the machine seems to be decent (and the fact that I promptly washed my receipt in my shirt pocket DOH!) I opted to deal with a few quality issues rather than go through the ordeal of trying to get replacements.
The first thing I identified was the crank handle for adjusting the table was drilled fairly off center so it wobbled badly and could not be pushed tight up against the casting.
This view shows pretty well how far off the hole is. I opted to make an arbor and turn the back of the handle arm true to the bore.

The next thing was more cosmetic than functional. When the table was cast, there was a lot of porosity at the sprue that resulted in perforations.
Structurally the table is sound so I gave it the old JB weld repair. I drenched the area in brake cleaner and wire brushed from the top side. When dry I put some duck tape on the bottom then mixed up the epoxy and spread it in. I don't plan to use much liquid but I figured chips would tend to get stuck and it would be harder to clean up after it had cutting oil and chips in it.
The third thing is closer to a functional issue. The pulley (all of them are metal) on the motor vibrated and worked the set screw loose. When I made a cursory examination with calipers I found the bore of the pulley to be .750" and the motor shaft to be .744". Most likely there is some taper in the pulley bore as well but I didn't feel like pursuing it further. I cut a strip of paper and ran it over the blade of a scissors to make it curl and sneeked it in between the shaft and pulley and that solved the wobble for now.
The cover is also all metal.
Now for the important question, does it work? I knocked the drill chuck arbor out and replaced it with a 1" taper shank drill bit. I clamped down a chunk of 1/2 x 1 1/2 1018 crs. After changing the belts to the orientation that indicates 180 rpm. I turned the machine on and hit it with the non contact tach, 180 spot on. I then drilled through using no pilot hole and minimal pecking. Once the bit got started the belt slipped, but after giving it additional tension had no further slippage.
The T slots are 5/8 and after a fairly aggressive clean up with files, mostly in the bottom of the "t", standard t nuts fit in all the slots. All in all with the ubiquitous 20% off coupon the machine was $448 + tax. The "identical" machine from Grizzly on sale with freight was $774 and the Jet was nearly $1k.
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