In a FWW article, Robert Vaughn describes “a precision rod of
known straightness… a hardened, ground-steel dowel” to detect run out with a dial indicator.
I’ve looked all over town, in all kinds of machine shops, screw stores, hardware stores and a few others. No one could supply me with this object.
The closest I found was on Amazon: a Starrett Standard End Measuring Rod but I don’t know if this is the thing.
Where does one get this mighty rod of straightness?
Thanks,
Burt
Replies
It's about $2- worth of ground rod - Bohler Uddeholm are the worldwide concern that carry it here - you may have a similar store (look under toolmakers in your local yellow pages and ask a toolmaker if you could bludge a bit or have him tell you a supplier.)
From memory, McMaster Carr are one US supplier that I seem to recall seeing on the internet, but I'm no oracle, so I could be wrong.
Cheers,
eddie
As long as you aren't contracted out to make parts for the Space Shuttle, just insert a bit and look for wobble as it spins a few hundred RPM. If it wobbles, try another bit to be sure you didn't grab one that's bent. You don't need precision to .000001 for drilling wood... :)
It helps a lot to be sure you tighten all the key positions evenly and not just tighten one and call it good. It can make a large difference in runout even in a good chuck.
Since the house is on fire let us warm ourselves. ~Italian Proverb
I just finished checking a DP today and used a 2 " flush trim router bit and ran the dial indicator on the bearing, .0005 was close enough to make me smile. Use what ya got.
Work Safe, Count to 10 when your done for the day !!
Bruce S.
The "real thing" is called precision drill rod, and you can get it from machine supplies such as mcmaster (http://www.mcmaster.com). As others have pointed out, for woodworking there's really no point in this kind of precision.
Pete
Here is another good supplier
.http://www1.mscdirect.com/cgi/nnsrhm??KNC-T7L391316886I don't know how you fellows are able to determine that Sutton doesn't need to bother with precision. If he didn't feel like his machine is within acceptable tolerance, how can you make that judgment without anything more than the has given?
If you are alluding to my post, I specified if he's drilling in wood. I reiterate that you don't need super precision for woodworking. If you don't SEE it wobble, you are good to go...for the Space Shuttle, more precision is required.
> I don't know how you fellows are able to determine that Sutton doesn't need to bother with precision...
Read the notes again. No one is saying he doesn't need to bother with precision; only that precision drill rod is not required to determine accuracy for woodworking.
Pete
Sorry, Spike and Pete. I guess sometimes how we interpret what we read depends on what we bring along from past experience, and some run-out should be expected, and accepted. However sometimes we run into problem tools that need to be corrected. I re-built an old drill-press a few years ago that had a lot of run-out, and was confronted with this very problem. I think I used a 12" long 1/2" drill. The flutes are only about 4" long, leaving 8" to work with. The problem I found with this tool was a ding on the morris-taper under the chuck, which caused over 1/8" of wobble at 8". It was easy to fix once I found it. I just filed off the bump, cleaned up the tapper, and re-mounted the chuck.
That's what I was getting at. If you can SEE a lot of runout, something needs attention. I sometimes create runout on purpose by placing a bit of tape on a drill's shank to make a slightly oversized hole when the exact size bit isn't available in my arsenal.
Edited 6/9/2006 11:45 am ET by Spike2
When I chuck a "regular twist" bit, run the DP, it appears to me that the entire bit is fuzzy. I also tested this with a brad point and could see the point blur. So, I'm assuming that there is run out.The major problem I'm having is drilling two 5/16" holes 7/8" apart along a straight line. The first hole always appears to be round while the second hole always appears slightly out of round and out of alignment to the line.I need to attach this drilled piece of oak to a metal base that has 8mm threaded holes (fine pitch). The metal base is unforgiving. If I'm not dead on, I can't screw in the bolts. The alinment must be dead on as well.As an additional test I took the same 5/16" bit and chucked it in a cordless drill. Got more accurately spaced holes, better alignment and more concentricity even though I could see a little wobble.My next test will be using what few router bits I have along with some quality Forester bits to test the run out on a dial indicator.All suggestions have been very helpful.Thanks,
Burt
It sounds like you've got significant runout, but you might be able to get by. It's curious that one hole is ok and the other is not. Is this perhaps due to difficulties holding the piece for the second hole? Can you use a fence to assure the holes are in line? Are you clamping the workpiece down before drilling? Pete
Are you certain that runout is your only problem? How about vibration, play, or improperly ground bit?Do you punch your starting point with an awl or center punch? Transfer centers placed in the threaded holes for punching your hole centers should add accuracy. Also, 8 mm. is greater than 5/16". You haven't mentioned how much clearance is allowed. Perhaps you would do better with the next larger letter- or number-size bit.Cadiddlehopper
Was just wondering if the quill has a lot of slop in the drill press head . Chris
That was my reference to play.Cadid
I would offer a word of caution in the allusion of drilling a larger hole with a shimed drill bit. This is a terrible practice. The only way to "drill" an oversize hole with a smaller bit is to sharpen it off center. If you are looking for a .031 oversize condition you only have to sharpen .015 off center. The off center condition allows the point of the drill to revolve around its "adjusted" axis with the one cutting flute longer cutting the extra without wobble and vibration. This shimming of the bit will produce a drill bit that no longer revolves around its axis but in "orbit" around the center of the drill chuck. In order to get the drill to cut you have to apply increased downpressure that actually deforms the bit to attempt to rotate around its axis producing wobble and vibrations. On a small drill you can smile at my warning but to the inexperienced individual that attempts this shimmed condition in a 1/2" millwaukee hand held drill using a 3/8 or larger bit into aluminum you have a problem. Drill sharpening for most shops is not in the realm of rocket science. There are no oilstones, waterstones, or tormek grinders to purchase. A clean grinding wheel and water and if you are really picky an eyeloop and a scale in 1/64,s. I am refering to a regular drill bit.
For a sturdy bit going into 3/4" material, I've had no problems. I wouldn't do that with an 1/8" bit into a thick piece of maple. <g>
Edited 6/9/2006 7:10 pm ET by Spike2
PeterBradley: As the workpiece is small, I am unable to hold it by hand, nor could I figure out how to hold it securely to the DP table. I had an old milling vise lying around so I used that. Worked fine as far as holding the piece securely and allowed me to accurately move the piece on an XY axis.At your suggestion, I went up to the McMaster site, found the precision steel rod and ordered it. Shipping was more then the price of the rod.cadiddlehopper: I found some play in the spindle but don't know how to fix this or determine if this is the problem. I only get the play by using a fair amount of force to wiggle it. The play is greater when the spindle is extended max, but visually, the spinning bit looks the same at min position & max pos.I tried using a 1/16" starter hole as well as punching with a brad. In both cases the results showed no improvement.While 8mm > 5/16", this size was found by how the bolt fit most snuggly into the hole as I'm trying to reduce as much drift as possible. (I don't have metric bits (yet)).So far, I've used 5 different bits including, Rigid, DeWalt, the set that came with the DP, a set from Area 51 and the brad point I purchased from Ace Hardware.
[ I found some play in the spindle but don't know how to fix this or determine if this is the problem. I only get the play by using a fair amount of force to wiggle it. The play is greater when the spindle is extended max, but visually, the spinning bit looks the same at min position & max pos.]
If the play is in the quill it can be fixed quite easily. First determine if the play is in the quill to housing bore . I would do this by extending the quill all the way down and shaking it . better yet would be be a indicator,By the way when the quill is extended all the way down raise it up a 1/4 " and then shake it/. If it is pushed down hard against the end of it's travel you woul not be able to feel the shake'.
So ' if it is loose i would remove the quill and fix it by drilling and tapping 3/8 -16 (3)holes at the bottom of the bore and at the top of the bore . Checking out casting thickness before drilling and tapping . you will need 3/ 8 casting thickness min for a 3/8 -16 hole . So you might want to start off with a 1/8" hole and stick a piece of wire in it .After holes are tapped and inside is deburred reassemble dp. then insert a short piece of 5/ -16 brass in each hole and addjust set screws until shake is gone. A piece of plastic any thing would work including probably wood dowel.
The turned, ground, and polished drill rod is probably the most accepted extension for this process but you might ask for "dowell pins". Most fab shops and large machine shops would utilize in detail assembly. Similar to roll pins and split pins but are ground to size. They come in various lengths(most common in 1" to 3" lengths) with left overs usually tossed in the shop roto-catchall . The "v" shape of the drill under light downward pressure tends to minimise the affects of runout at least for the first hole as the cutting edges are centered as they cut. That second cut with a slightly larger drill is a bear without a "lead" to get started. Larger diameter and longer drills can be dangerous as they can grab especially aluminum. good luck !!
Burt,
What type of drill press do you have ? I own an automotive machine shop and am used to pretty close tolerances. Most of the drill presses I have seen in Sears etc really are not that great as far as runout goes. I have a Wilton at home for woodworking etc and it stinks. Part of the problem could be the chuck itself. Try removing it and see if you can measure the runout of the spindle. Sometimes removing the chuck, cleaning everything, and reinstalling it will help.
Hope this helps,
Bill Koustenis
Advanced Automotive Machine
Waldorf Md
Bill,
I have a Grizzly G7944 12 speed. This is the low end of their floor model. The belt at its lowest setting, which I believe is 500 rpm +/-.I have taken the chuck off the spindle but did not remove the arbor from the chuck so cleaning it was not a successful chore. I will probably attempt this again and remove the chuck from arbor to give it a good cleaning. I did notice an improvement of a few thou when I reinstalled the chuck.Grizzly tech support said that .006 (which was the best I could get) was a very decent number for run out. But after reading the Robert Vaughn article I was tempted to reduce run out to .002. To facilitate this I ordered a precision steel rod from McMasters. It will arrive on 6/14/06 (which is tomorrow at time of writing) so I can't do the full procedure yet. But I will report the results either way.I will admit that for general drilling into wood, I never had a problem until this project. Funny thing is, the solution was a $1.15 hose clamp and it worked perfectly. However, if I can get better specs on run out, I will go for it.Thanks,
Burt
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