Few questions on 3/4 round dog holes

[Dan Karachio]

Okay, drilled some 3/4 dog holes a while back and now notice they are getting tighter with humidity. Some too tight. 2" thick maple top. Do I dare redrill only to have them too loose in the winter when it dries up? I have a dehumidifier - should I get the shop (basement) to some level of humidity then drill? It ran up to 75% for a few days when I forgot to plug in dehumidifier, but is now back to 55% and the tight holes are still too tight.

Next. It may seem picky, but are any 3/4 dowels really 3/4"? I want to build various jigs and stops using 3/4 dowels. I have purchased dowels from Woodcraft. Lowes and Home Depot and none are truly 3/4". All are too large. Does anyone sell truly accurate dowels? I'd like them for other things as well. I don't have a lathe and if somehow hand sanding these down is my only option, please let me know.

[Chuck Nickerson]

As for accurately sized dowels, The best I know are available through Beall Tools (google will lead you to their website). Their accuracy does come at a price.

[David Keller NC]

Dan - I ahve almost the exact same problem with dog holes - I built a new bench last Fall with a 2-3/4" maple top, and drilled 3/4" holes with a ship auger bit, which was just a hair over 3/4". I have a basement shop, and the humidity is controlled with a de-humidifier. Last fall, the humidity was relatively constant at 35%. Now with summer weather making its arrival, the shop stays at 50% R.H. and the dog holes were quite tight.

If you're using the L-V brass bench dogs, you should be OK with enlarging the holes - I know for sure that they will accomodate 7/8" diameter holes on some of my jigs. If you're using wooden dowels as dogs, you will probably have to install some sort of spring mechanism to get them to work in all conditions.

As to enlarging the holes, I would not recommend attempting to re-drill them. Once there's already a hole there, a bigger drill bit, whether ship auger, forstner, brad point, or split-twist, will not have anything to register on, and won't work. You can put together a maple block jig to hold the bit still while you drill, but then you've the problem of precisely lining up the hole in the jig with the hole in the bench.

The best way to expand the holes in your bench, in my opinion, is to use a half-round rasp (and it's a great excuse to buy an Auriou or The Best Things modeler's rasp - they're handy for so many uses around the shop). Failing that, you can use a round chainsaw file, or construct a sandpaper flapper out of a small dowell and some 100 grit sandpaper.

If you use this last method, be aware that it will be slow - maple is very hard, and about 1/4 of the hole is end-grain. In fact, you may find that this method results in egg-shaped holes, as the end grain doesn't sand much, but the side grain does.

As to the dowels, the reason you're seeing not-quite-round and oversized dowels has to do with the way they're made. Instead of a lathe, they're forced through a die plate, which compresses the wood fibers somewhat, and they then spring back a little on the other side. The out-of-round condition usually has to do with expansion/contraction with humidity changes.

[Jim Koepke]

My bench is European, for some reason the holes are 18 mm instead of 19 mm (3/4 inch). The easiest thing to do is to reduce the dowel size.

There are a few ways to do this. One can do a crude lathe set up by drilling a 3/4 inch dowel and gluing a smaller dowel in the center then chuck it up in a drill motor. Sand away and test the dowel while in process.

jim

[Richard Dooling]

I sand or use a spoke shave to reduce the diameter then put a very small, spring loaded bullet (ball) catch in the side so it doesn't fall through the hole.

I would only attempt to enlarge the holes if they did not fit my brass bench dogs anymore.

.

[glenn bradley]

I do what Richard does.

http://www.sawmillcreek.org/attachment.php?attachmentid=102897&d=1228504888

A machine shop fit is not really required IMHO.

[harry strasil]

counter sink the top of the hole a bit to let the bit find its own center, so it doesn't wander on start up, or use a reamer.


I drilled the holes in my NuBench 13/16 inch as I made my hold downs out of 3/4 hot rolled bar and its oversize, with the slightly larger hole all I need to do to make the holdfast work is to push on it with my hand, but a light tap with a mallet really sets it solid.

[sean m. titmas]

my inexperience with round bench dog holes might be showing through but, what about drilling the holes to accept a sleeve of some type. like PVC, brass, plastic resin or steel pipe. the sleeve would keep the ID of 3/4" to remain consistent.

go or no go?

[glenn bradley]

my inexperience with round bench dog holes might be showing through but, what about drilling the holes to accept a sleeve of some type. like PVC, brass, plastic resin or steel pipe. the sleeve would keep the ID of 3/4" to remain consistent.

go or no go?

The benches at the LV LN hand tool demos at the show this year had brass inserts as you describe.

[Louis Reed]

Richard,

Where did you buy the spring loaded bullet device ? That was a good idea for holding the benchdog in place.

Louis

[Richard Dooling]

Got them at Woodcraft. They are catches for small doors. I wish I could take credit for the idea but I read it in a "tips" section of one of the woodworking pubs.

[David Keller NC]

"my inexperience with round bench dog holes might be showing through but, what about drilling the holes to accept a sleeve of some type. like PVC, brass, plastic resin or steel pipe. the sleeve would keep the ID of 3/4" to remain consistent."

Sean - I think there are some drawbacks to this approach, and whether it'd be advisable to do it depends on what you want to use the dog holes for. For a holdfast of traditional construction to work, it needs "grip" on the top and bottom of the dog hole. That friction causes the shaft of the holdfast to flex slightly, which maintains a firm, spring-loaded grip. If the inserts were too smooth, you might have issues with getting holdfasts to do their thing.

Regarding using dogs in the holes with sleeves, I'd note that unless the insert were very strong steel, they wouldn't acutally prevent the internal id from changing as the wood swelled - that force is driven by the hydraulics of the moisture that gets absorbed into the wood, and as water is (nearly) incompressible, something's going to give. If the insert is brass or plastic with a wall thickness of less than about 3/16" an inch, I'm pretty sure that the inserts would just deform with the wooden outer hole.

If the inserts are very strong, it may well be that the wood will deform, and possibly crack, depending on how close the hole is to the ends of the bench.

In my case, I just coughed up the cash for 4 Veritas brass dogs that are held with springs, so it doesn't matter if the dog hole contracts/expands by a 1/16 of an inch or so. If I was using wooden dowels, I'd probably go with either a wooden spring set into the dowel, or a bullet catch as was suggested above.

[Dave Matson]

Lee Valley also sells bullet catches:

http://www.leevalley.com/wood/page.aspx?c=2&p=58949&cat=1,44047

A good deal. Hard to imagine having a need for 100 Dogs ;)

[Richard Dooling]

Hey Louis,

I have extras. PM me and I'll send you a few.

[Dan Karachio]

Thanks! I thought for sure I was the only one with this problem.

Question please, what I meant to ask was what about redrilling with the same exact bit I used originally? With the LV dogs, some holes are now tight with others just fine. Same goes with the actual bit that was used to drill these (3/4 brad). Seems like using the same bit might be safe enough as long as I have the humidity stable - right? Maybe?

[Frank Townend]

I have purchased dowels from American Wood Crafters Supply (http://www.americanwoodcrafterssupply.com/wooden-products/dowels.htm#Dowels) and they have been spot on for the stated diameter. The have a nice assortment of sizes from 1/8" through 2".

[Louis Reed]

Thanks guys for the reply on were to buy the catches.

Louis

[Andy Bardowell]

I have a crazy idea for re-drilling them Dan the other guys can comment on the soundness of it and you can try it on scrap first. See if you can find a 13/16 bit, then if you have a ½” flush trim bit with bottom bearing, try to find a 7/16” bearing, this way you can cut a small rabbet to start the larger bit. Now how to keep the big bit from wondering, something shop made or a drill guide but something that you can clamp so it won’t move.

[Dan Karachio]

Just a FYI. First, Chuck the Beall dowels were spot on! Thanks! Second, running the old dehumidifier has gotten the holes all back to normal.

I'm still not sure what to do or recommend about humidity at the time when one drills, but obviously it is a factor. Yet another potential screw up I narrowly avoided.