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Forum topic by spunwood posted 936 days ago 873 views 0 times favorited 16 replies Add to Favorites Watch
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spunwood

1193 posts in 1431 days


936 days ago

If a hole is 3/8” exactly, will an exactly 3/8” dowel fit in it?

If a mortise has the same exact dimensions of the tenon, will they fit together?

-- I came, I was conquered, I was born again. ἵνα ὦσιν ἓν


16 replies so far

View CharlieM1958's profile

CharlieM1958

15639 posts in 2814 days


#1 posted 936 days ago

I would say, theoretically, the answer is a definite yes. The real question is how tight the fit would be.

-- Charlie M. "Woodworking - patience = firewood"

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Don W

14592 posts in 1163 days


#2 posted 936 days ago

it would fit, but there would be no room for glue. If the dowel was slightly bigger it would still fit, you’d just need a bigger hammer.

-- Master hand plane hoarder. - http://timetestedtools.com

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DaveBaker

65 posts in 2347 days


#3 posted 935 days ago

Technically speaking, it will not. You will have what is referred to a line to line fit. The dowel needs to be just a little smaller or the hole just a little larger.

It is surprising how much a difference .0001” can make. Also how much “slop” there seems to be in a hole that is say .100” when checked with a .0995 pin gage.

-- Upstate New York -- Do what you love and never work a day in your life.

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StumpyNubs

6114 posts in 1396 days


#4 posted 935 days ago

If we were talking about metal, it would take several tons of force to fit it in, less with lubrication. But wood compresses rather easily compared to metal, so it fits much easier.

-- It's the best woodworking show since the invention of wood... New episodes at: http://www.stumpynubs.com

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doncutlip

2832 posts in 2151 days


#5 posted 935 days ago

Stumpy – first thing I thought of was metal, so you beat me to it. What if it was wood painted to look like metal?

-- Don, Royersford, PA

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StumpyNubs

6114 posts in 1396 days


#6 posted 935 days ago

Don- that would be a problem, especailly if you were trying to make it fit while listening to heavy metal…

-- It's the best woodworking show since the invention of wood... New episodes at: http://www.stumpynubs.com

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RickRogers7

39 posts in 1633 days


#7 posted 935 days ago

If both the hole and pin are perfectly 3/8 and perfectly straight, then theoretically yes. It is a line to line fit and would be very difficult to assemble. If I did that to the folks I work with on the assembly line I would get lots of unfavorable comments, and learn some new adjectives that could not be repeated in church.. If your interested you can look up recommended hole clearances , depending on the type of fit you want, in a book called the Machinists Handbook. This book has been around much longer than me and has lots of cool stuff in it.

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poopiekat

3552 posts in 2330 days


#8 posted 935 days ago

What if it was ironwood?

-- Einstein: "The intuitive mind is a sacred gift, and the rational mind is a faithful servant. We have created a society that honors the servant and has forgotten the gift." I'm Poopiekat!!

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pierce85

508 posts in 1158 days


#9 posted 935 days ago

I’m with DaveBaker on this one, and poopiekat’s example is a good one. However, RickRogers7 has given me some doubts.

Great question, spunwood.

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StumpyNubs

6114 posts in 1396 days


#10 posted 935 days ago

Hey, Poopie... what did I ever do to get blocked by you?

-- It's the best woodworking show since the invention of wood... New episodes at: http://www.stumpynubs.com

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RickRogers7

39 posts in 1633 days


#11 posted 935 days ago

Im actually with Dave on this too. I suspect were approaching the same idea on a slightly different path. There are no perfect holes, pins, or calipers to measure the pins and holes. So it’s always a good idea to have enough clearance to cover the tolerance the holes and pins (dowels) can be made to.

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jeffl

283 posts in 1906 days


#12 posted 935 days ago

I’ve sanded my 5/8 drill about. 010 undersized and turn the tenon on size and with a little glue ” for lubrication only ” and a dead blow hammer it fits. Forever I believe.

-- Jeff,

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StumpyNubs

6114 posts in 1396 days


#13 posted 935 days ago

cr1- actually,when they first came out with STP oil treatment the salesman would go around demonstrating how to put a 1 inch pin in a 1 inch hole. They had a devise that measured how many tons of pressure it took to do it dry, and then showed how much less it took to do it when lubricated with STP.

A piece of metal that is machined perfectly flat will slid across the surface of another piece of metal even though there is precisely zero space between them. It’s the same concept with a peg in a hole. There doesn’t have to be any space, you just have to overcome the friction.

Of course one may argue that there has to be at least enough space on a microscopic level for the oil molecules to fit between the surfaces…

-- It's the best woodworking show since the invention of wood... New episodes at: http://www.stumpynubs.com

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poopiekat

3552 posts in 2330 days


#14 posted 935 days ago

I recall from a shop manual for rebuilding the engine on a 195.6 c.i. OHV engine on a 1960 Rambler, how to check tolerances on the connecting-rod wrist pins without actually measuring: ”If the pin will slide freely in and out of the wrist-pin bore of the piston when clean and dry, but will not slide freely of its own weight when lubricated, that is an indication that the wrist pin-to-bore clearance is correct.” More worthless info stuck in my head, but the bigger conversation is the RANGE of tolerance, where the min/max of the dowel and the min/max of the hole may or may not fit right due to stackup of tolerances on two separate parts.

-- Einstein: "The intuitive mind is a sacred gift, and the rational mind is a faithful servant. We have created a society that honors the servant and has forgotten the gift." I'm Poopiekat!!

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racerglen

2254 posts in 1376 days


#15 posted 935 days ago

And never forget all dowels aren’t the same.
The variation in size among the commercial ones is astounding.
But that’s not realy the point here..

;-)

-- Glen, Vernon B.C. Canada

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