Runout measurement of Dremel Drill Press Stand

Since I'm trying to determine if I need to upgrade my trusty old drill press
(~35 year old AMT 10" Bench) to something with more precision -- since I'm
regularly drilling #70's for PC board holes and have a future need to go up
to #90 or so -- I measured it's runout over the weekend. Runout was a
little less than +-0.0015" or just under .003" total. I was advised that
it's about as good as could be expected, but I felt that I needed more so I
said, "Hey, I've got an old Dremel drill press stand that I've used for
years. Maybe it's better."
One part of the measurement is a little unorthodox -- I had to measure it
with the unit running. Okay, I was using the Dremel benchtop speed control
set to absolute minimum and I don't think it was running more than about
50-60 RPM [visually about 1 second around], but since it's a direct drive
and the motor is enclosed in the hand tool's housing, it's the only way to
get it to go around without actually putting a finger on it and turning it
which also pushes the shaft sideways.
But the results were no better than the bigger unit. I watched the needle
on the dial indicator wiggle between two readings that were exactly .003"
apart and the rate of motion was similar to what I saw as the rotational
speed of the shaft.
With that much runout, I'll never be able to drill down in the #80's with
carbide bits -- except maybe for making pinholes in .002 brass sheet [which
is one use I'm going to have].
But the bottom line is that I'm going to need something considerably better.
I guess I'll watch eBay for a week or two to see if anything turns up and if
it doesn't I'll probably have to start pitching quarters in the jar to save
up for the new unit.
Thanks for all the suggestions.
Norm
Reply to
Norm Dresner
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I've got 3 or 4 dremels if you want to bring over your DP stand and spend a little time checking runout on all of 'em, maybe it's a little worn?
GWE
Reply to
Grant Erwin
| > Since I'm trying to determine if I need to upgrade my trusty old drill press | > (~35 year old AMT 10" Bench) to something with more precision -- since I'm | > regularly drilling #70's for PC board holes and have a future need to go up | > to #90 or so -- I measured it's runout over the weekend. Runout was a | > little less than +-0.0015" or just under .003" total. I was advised that | > it's about as good as could be expected, but I felt that I needed more so I | > said, "Hey, I've got an old Dremel drill press stand that I've used for | > years. Maybe it's better." | > | > One part of the measurement is a little unorthodox -- I had to measure it | > with the unit running. Okay, I was using the Dremel benchtop speed control | > set to absolute minimum and I don't think it was running more than about | > 50-60 RPM [visually about 1 second around], but since it's a direct drive | > and the motor is enclosed in the hand tool's housing, it's the only way to | > get it to go around without actually putting a finger on it and turning it | > which also pushes the shaft sideways. | > | > But the results were no better than the bigger unit. I watched the needle | > on the dial indicator wiggle between two readings that were exactly .003" | > apart and the rate of motion was similar to what I saw as the rotational | > speed of the shaft. | > | > With that much runout, I'll never be able to drill down in the #80's with | > carbide bits -- except maybe for making pinholes in .002 brass sheet [which | > is one use I'm going to have]. | > | > But the bottom line is that I'm going to need something considerably better. | > I guess I'll watch eBay for a week or two to see if anything turns up and if | > it doesn't I'll probably have to start pitching quarters in the jar to save | > up for the new unit. | > | > Thanks for all the suggestions. | > | > Norm | > | | I've got 3 or 4 dremels if you want to bring over your DP stand and spend a | little time checking runout on all of 'em, maybe it's a little worn? |
Actually I have IIRC 2 other Dremel tools as well but the oldest one is the one I've kept in the DP stand for the last two or three years. Since you've given me an idea, I should check at least the newest one to see if it's any lower.
Thanks Norm
Reply to
Norm Dresner
I highly recommend these MicroMark units for precision drilling:
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the wraps... JR Dweller in the cellar
Norm Dresner wrote:
Reply to
JR North
According to Norm Dresner :
Actually -- the suggestions were that you should *augment* your old drill press with an additional sensitive drill press. There are things which your current drill press will do better than a sensitive drill press, and things at which the sensitive is undoubtedly superior. And, the sensitive drill press does not take that much bench space so as to need to dispose of the older drill press.
[ ... ]
And -- if this pressure deflects the spindle, it is not a sufficiently solid set of bearings. (Of course, it could also deflect the mounting of the plastic housing in the drill press stand.)
O.K. Where were you measuring? Ideally, you should be measuring the inside of the taper on the end of the spindle. Otherwise, on the OD of a shaft held in the collet -- except that includes errors introduced by the collet itself -- and the Dremel collets which I have seen are not ground it the kind of finish that a quality collet would have, so I would expect increased runout from the collet.
Patience will turn them up. A friend needed one, and after about a month, he got one from one of the other members of the local metalworking club (a nice DuMore), and within the week, two showed up on eBay for about half what he paid. (He still got an excellent tool for a quite reasonable price.)
BTW If you find one without a hole in the table, I would suggest that you add a piece of wood to back up what you are drilling, so you never make holes in the table.
For the ones which currently show up on a search for:
"Sensitive drill press"
(quotes included), the best choice at present appears to be auction #7596471948, which is currently at $51.00 with reserve not yet met.
*Personally*, I would look for an appropriate Albrecht 0-1/8" (0-3mm) chuck to replace the current one. Note that those chucks are available both with a JT-0 and a JT-1 taper, so be careful which you bid on. I suspect that this drill uses a JT-0 taper, but check the markings on the machine if you get it.
If you use the above keywords *without* the quotes, I would suggest that you add the following:
-earring -gps
to reduce the number of false hits.
Note that some of the things which the sellers are calling "Sensitive drill press" are not things which I would so call.
The later search does show up a couple of others which might be worth checking out if you lose the first one -- auction numbers:
7596199228
and
7596221211
But both are set with an opening bid of $300.00, and the photos are terrible, so unless you are close enough to Shakopee Minnesota to be able to drop by and examine them personally, I'm not so sure. Given that they were used as circuit board drills, they sound like what you need.
Good Luck, DoN.
Reply to
DoN. Nichols
According to JR North :
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And:
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A) Too large (and too cheap) a drill chuck. It is a 1/4" one with the pressed-steel body cup instead of a properly machined one. (And is likely to be a threaded attachment to the spindle, which is likely to have more runout.
B) Too slow a maximum spindle speed for the drills which he is using. it only goes to 6000 RPM -- not the 30,000 needed for those tiny drill bits which he is using.
Enjoy, DoN.
Reply to
DoN. Nichols
True, I forgot I replaced the chuck on mine first thing. Anyway, he doesn't need 30k rpm to drill pcbs. JR Dweller in the cellar
D> According to JR North :
Reply to
JR North
| According to Norm Dresner : | > Since I'm trying to determine if I need to upgrade my trusty old drill press | > (~35 year old AMT 10" Bench) to something with more precision | | Actually -- the suggestions were that you should *augment* your | old drill press with an additional sensitive drill press. There are | things which your current drill press will do better than a sensitive | drill press, and things at which the sensitive is undoubtedly superior. | And, the sensitive drill press does not take that much bench space so as | to need to dispose of the older drill press. |
Since most of the sensitive drill presses I've seen so far have only a 1/4" chuck, there's no way I'd give up the 1/2" on the old one. But I'm fortunate in having two "workshops" .. a 10' x 18' for big stuff and a 6'x12' for small "crafts" ranging from model building to electronics construction and testing. If I buy anything like a sensitive drill press, it'll go in the small room.
Norm
Reply to
Norm Dresner
According to Norm Dresner :
The better ones will have a 1/8", or perhaps a 5/32" one.
If you are drilling G-10 or one of the other glass-epoxy PC board materials, be careful of the dust formed by the drilling, as it can be quite abrasive, and destructive to the ways of a lathe or a milling machine.
Good Luck, DoN.
Reply to
DoN. Nichols
Right! - It is SiO2 - glass. It is also un-healthy to breath. Bad for oil pumps but better for them than the lungs.
Martin Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH & Endowment Member NRA Second Amendment Task Force Charter Founder
D> According to Norm Dresner :
Reply to
Martin H. Eastburn

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