Drills for Ligero Kit.

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wdcav1952

wdcav1952

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I don't have a 17/32 drill for the Ligero upper barrel. Will the 13.3 mm drill Ernie at Beartoothwoods.com sold me some time back work as a substitute? It seems to work OK given a test drilling I did, but since I am using ar really nice afzelia lay blank for the kit, I thought I would ask first.

Thanks in advance,
 
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The difference in the two drills is tiny. 17/32 is 13.49375 mm. Put the other way, 13.3 mm is approximately 0.5248 inches and 17/32 0.53125. I would test fit the parts in your scrap but I'm betting that .007 inches is reasonable tolerance for barrel diameter.
 
Well now, you are getting into my area of expertize..... the dollar 98 Wal-Mart calculator!! Lou missed a button his abbacus..... 13.3 mm is actually 0.5236". As to his comment about 0.007" being a reasonable tolerance, I would say it depends. In this particular case the proposed substitute drill is about 0.007" undersize, so the real question is whether or not your tube will fit in an 0.007" undersize hole. If the tube fits, then the 7 thou tolerance is OK. If the tube doesn't fit, then the tolerance is not OK.

Where the question of tolerance gets more critical is when you are proposing an oversized bore. Clearly a tube will fit in a 0.007" oversized bore without any problem, whatsoever. The question there is whether that oversize gap is too big to give you a good strong glue joint. I don't know what the specs are for the width of the glue line for the three commonly used pen adhesives; but would be willing to bet there is a member here who does. What I do know is that when different kit manufacturers specify different drill sizes
(like a letter drill vs. a metric one) the difference is usually
2-3 thousandths Whether that gives us a clue about the needed thickness of the glue line, I just don't know.

For those who are interested in having an easy reference to see how the various drill systems compare, order a catalog from www.hutproducts.com . There is a very useful chart in the middle of the catalog that shows the comparison of fractional, letter, wire gageand millimeter sized drills. Maybe someone with a scanner could get permission from HUT to post the chart here??? And if you are more atuned to electronic references, check out this site http://www.carbidedepot.com/formulas-drillsize.htm .
 
OK, I freely admit that you guys can do fractions much better than I. LOL When I use my 13.3mm drill, evrything seems to vibrate more than usual, and the top half inch (approx., no decimals.) is a little oversized. After that, the hole is the right size. Is this a warp in the drill? It has always been a problem since I got the drill. I used poly glue, and pushed the tube as far from the initial part of the hole as possible. Would I do better to toss the 13.3mm drill (it was relatively expensive) and get a 17/32?

Thanks,
 
Originally posted by DCBluesman
<br />Or get the same chart in our Reference section. See the upper right hand side of the home page!
Click to expand...

I think it may be "UPPER LEFT"???

I have to admit to a bad habit of bookmarking forum pages and bypassing the home pages of many web sites. Guess I'll have to quit doing that as I occasionally do miss good information!!!

Lou: Someone needs to fix two of the links on the Reference page.

<u>What Tree Is It</u> link has changed and needs to be updated.

<u>International Wood Collectors Society</u> link does not work at all.

All of the other links seem to work OK and and have a lot of good information!!!
 
I meant my "other" right, Randy. And we'll get thos links fixed! William...I'd check the level of your drill press table, then check the roundness of the bit. As for the 17/32 bit, it's used for several pen kits, including the Gent Jr and the Baron if I'm not mistaken). If you plan on making those pens, it might be worth the investment.
 
William:

It does sound like your drill bit may have a problem; but it's hard to know for sure. Do you have a hard flat surface available to you.....table saw table or piece of glass?? Roll the drill on a flat surface and see if it rolls smoothly or with a little wobble and a clicking sound. You should probably be able to detect a warped bit either visually or by the sound it makes. Roll a bit that you think is good for comparison.

Two other thoughts. I would think that a warped bit would produce a hole that was screwed up throughout its length, not just at one end. And you might try chucking the bit in your drill and running it at a slow speed to see if you can detect a "wobble" visually. And finally, if you are not sure, like you say, bits are cheap(at least the small ones are), buy another one of the recommended size and put the ?? one in the wife's tool box!!!
 
And just a few more words about tube clearances. According to the HUT catalog, they call for a 9/32" bit(0.281") for the 7mm kit which has a brass tube with an OD of 0.266". That would result in a glue line gap of 0.15"/2=0.0075". I have also seen 7mm kits for which the recommended drill size was either 7mm(.2756") or letter "J"(.277").
 
Originally posted by wdcav1952
<br />OK, I freely admit that you guys can do fractions much better than I. LOL When I use my 13.3mm drill, evrything seems to vibrate more than usual, and the top half inch (approx., no decimals.) is a little oversized. After that, the hole is the right size. Is this a warp in the drill? It has always been a problem since I got the drill. I used poly glue, and pushed the tube as far from the initial part of the hole as possible. Would I do better to toss the 13.3mm drill (it was relatively expensive) and get a 17/32?

Thanks,
Click to expand...


I did overcome to this problem, when you drill a 3/4"x3/4" with a 13.3 m/m drill bit you have an oversize hole for start and you don't have much thickeness on the side of the blank( around 7/64 thick of the blank each side ), so what I do is take a scrap of pine wood cut the same size of the blank, glue it with wood glue and news papper between, drill the hole, if the bit wonder at the starter is not a problem, I separated the pine portion and throuw out then you have a strait hole on your pen blank, I know is a bit macking around but when you drill a $ 6.00 or more blank is worth the extra work and the tube fit perfectly.


Serge
 
Some wallowing out at the top of the hole is a fact of life, and there are a lot of reasons for it happening.

The friction of the compacted chips as they escape from the top of the hole can errode the wood around the top of the hole, or they can compact the wood into a larger diameter, or the heat could expand the wood into the drill so that it is a larger diameter after it cools.

Or, it can be from the drill bit growing to a larger diameter from the friction heat.

The most likely cause is from the drill having to re-center itself back into the hole after it has been lifted to clear the chips.

Why did it move off-center??
Could be that the drill is wanting to follow the grain in a direction other than straight. Could be that the wood moved if it isn't clamped securely to the table. Could be a bent drill (if the tip wobbles as it spins, it isn't straight).

And it could be that the drill couldn't drill a straight hole if it wanted to. There could be a misalighment between the tailstock and headstock if drilling on the lathe, or it could be too much slop in the spindle if drilling on a drill press.

Like break-out at the bottom of the hole, this wallowing out at the top of the drilled hole can be resolved by cutting the blank "long" and then trimming to length AFTER drilling the hole.
 
The method that I use to stop the drill from wandering is to pre-drill a lead hole with a 1/8" Brad point bit about 1/8" deep . This gives the regular drill bit something to follow and prevents it from going where it wants to . I just mark the center of my blank then drill the lead using a hand held drill . Works every time . I turn a lot of angle cut Dymondwood and this is the method I came up with to prevemt wandering .
 
To high a speed will also make the top of the hole larger, I did it yesterday by mistake. I was just really lucky that I had left the blank a little long because it was a blank that I just got from Rich and it was the best of the bunch.

Wayne
 
I still don't know why it does it. I was clamped very securely to the table. This is the only drill that has the problem. Today I looked at the tip under good light, and I notice that at the tip of the drill bit there is some roughness on the flutes as if something had dried on the metal. I don't have a Drill Doctor, but I will have a 17/32 drill ordered today.
 
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