How to drill square holes (90deg, not mortises) in the field...

[Michael Dunn]

Here's one way. I've had a few live edge slab mantles to install in recent months. I used my 12" brad point bit and just eyeballed my 'straightness'. My first attempt was pretty accurate. My second... Not so much.

In an effort to increase efficiency and accuracy of my drilling 'in the field' I thought of this idea. I'm sure it will evolve as I put it to use.

This design in particular is pretty beefy as I used 4x4s, T-track, and some jointed 2x4s to keep things square against the reference edge of the workpiece. I will of course use clamps to secure this to the workpiece.

I have a large Doug Fir rustic table I'm building for a client. He's providing the boards. I they're in house condo already. 5th floor. Elevator or not, I did NOT want to bring these to my shop. Yet I need to drill 1/2" diameter holes through the width of the boards. This is for a 1/2" threaded rod to be inserted to have nuts and washers on each end to bring the boards together more securely in addition to the cleats on the trestle style base I designed.

So now I can use my guide to get the hole started nice and square to the faces, remove the guide and drill the rest of the way through. I do for see a potential alignment issue as these boards are not jointed, ripped, and planed. So while this jig will certainly allow me to drill one hole perfectly. The exit hole of the first needs to line up perfectly with the entry hole of the next while still being centered in the thickness allowing for the tops to be relatively even and flat.

Any thoughts on the last part are welcome... I guess since the boards are 4x12 (I just realized that I had yet to mention that fact... Duh!!!) my 12" bit should make it though just enough to make a mark on the next board. Or I can just carefully layout the hole locations.

[Pat Barry]

I wonder how well you can keep a 1/2 drill on line thru 12 inches of material thickness, therefore, my suggestion would be to drill approx 1/2 the depth from each side and meet in the middle. If need be, to ensure the 1/2 rod fits nicely, you can chase the first hole back through to the middle to clean up the transition. Advantages I see are that you can get the entrance hole on each side of the board exactly where you want them.

[Richard Coers]

I'm going to wait for Phil Thien to pat you on the back before I mention something that you are forgetting about wood.

[Jeff Duncan]

I'm not sure I get the use of the threaded rod.....are you not gluing the boards together?

JeffD

[Michael Dunn]

I'm not sure I get the use of the threaded rod.....are you not gluing the boards together? JeffD

He wants the threaded rod for an 'industrial' look. I figured I'd make it useful as well. I wasn't planning on gluing them being that it's a rustic, old looking piece.

Clear your PM's...

[Michael Dunn]

I'm going to wait for Phil Thien to pat you on the back before I mention something that you are forgetting about wood.

Yes, I know. Wood expands and contracts with the change in moisture. I read that in book on 'woodworking fundamentals'. After I glued and nailed the squaring blocks I realized I should've butted the end grain up against the guide block with the guide hole.

Or is there something else?

[Phil Thien]

Yes, I know. Wood expands and contracts with the change in moisture. I read that in book on 'woodworking fundamentals'. After I glued and nailed the squaring blocks I realized I should've butted the end grain up against the guide block with the guide hole.

Or is there something else?

What he is getting at is, if you capture the wood between nuts on the end of the threaded rod, you may have a problem with expansion/contraction.

Of course, some workbenches are produced exactly that way:

http://www.popularmechanics.com/home/how-to-plans/woodworking/4219723

When I was a kid we had a book that illustrated that method of assembly. My memory is foggy, I had thought they removed the all-thread AFTER the top was assembled.

[Michael Wildt]

Some thoughts on this, assuming I'm understanding your description correctly.

The sides of each board must be parallel before you drill these holes. If not then you'll never get the holes to align for the rod to be inserted all the way through the x number of boards you're putting together. Either bring the boards to the shop or 'fake' the bolt look by only doing it on the first and last board. Then use a domino/spline/bisquet to align the boards and then potentially glue them together.
Or put them together, temporarily, then snap a line across all of them that you can use as a reference for the guide you have created. That should assure the holes on the boards align a bit better than complete free hand.

I'd also use castle nuts on the threaded rod so you don't get hurt by accident. Even if you file the cut off end nicely it could still snag on a piece of clothing.

I'd also put a drill bushing into the guide you made since that initial hole will no longer be 1/2" after 3-4 holes are done.

[Brian Tymchak]

I'd also use castle nuts on the threaded rod so you don't get hurt by accident. Even if you file the cut off end nicely it could still snag on a piece of clothing.


How about recessing the rod end and nut into the edge of the table so as to not protrude? Even if you get the rod end smooth, I feel like it could still be an annoyance for anyone leaning into the table edge.

[Michael Dunn]

How about recessing the rod end and nut into the edge of the table so as to not protrude? Even if you get the rod end smooth, I feel like it could still be an annoyance for anyone leaning into the table edge.

I'm sorry. I forgot to mention that the nuts will in fact be recessed. The other side of the drawing actually shows the recessed forstner holes.

[Michael Dunn]

Some thoughts on this, assuming I'm understanding your description correctly. The sides of each board must be parallel before you drill these holes. If not then you'll never get the holes to align for the rod to be inserted all the way through the x number of boards you're putting together. Either bring the boards to the shop or 'fake' the bolt look by only doing it on the first and last board. Then use a domino/spline/bisquet to align the boards and then potentially glue them together. Or put them together, temporarily, then snap a line across all of them that you can use as a reference for the guide you have created. That should assure the holes on the boards align a bit better than complete free hand. I'd also use castle nuts on the threaded rod so you don't get hurt by accident. Even if you file the cut off end nicely it could still snag on a piece of clothing. I'd also put a drill bushing into the guide you made since that initial hole will no longer be 1/2" after 3-4 holes are done.

I was thinking about a guide bushing too. As for the edges being parallel. I'm well aware of that. However, my client wants a rustic look and wants to retain the rough edges of all of the boards.

Me personally, I prefer clean lines, jointed, ripped, and planed boards and glue. Not so with this client.

[Michael Dunn]

What he is getting at is, if you capture the wood between nuts on the end of the threaded rod, you may have a problem with expansion/contraction. Of course, some workbenches are produced exactly that way: http://www.popularmechanics.com/home/how-to-plans/woodworking/4219723 When I was a kid we had a book that illustrated that method of assembly. My memory is foggy, I had thought they removed the all-thread AFTER the top was assembled.

Right. I'm aware of that as it was mentioned in some books on WW'ing fundamentals I just read 5 minutes ago... Just trying to stay at the top of my game. Tee hee...

I considered that movement as well, but I thought he was referring to my jig.

[Ethan Melad]

I considered that movement as well, but I thought he was referring to my jig.

so, if you considered that movement, did you come up with a solution? i'd hate to see this guy's wood split or check in the spring when all of a sudden the humidity changes.

and there are plenty of ways to build a 'rustic' table with (or without) edge gluing that would accommodate for wood movement...
profile corners before gluing, scraping the top, or, maybe easiest, build your base so each board is attached with a fastener that allows for movement...you could find some way to incorporate the 'industrial' look in a way that does not involve the construction method.

edit: oops mixed up my seasons...not as likely that wood will split upon expansion...but if the rods were tightened way down when the expansion occurred, maybe that could do it.

[lowell holmes]

Google "Big Gator V Drill Guides".

That will keep them square.

[Perry Holbrook]

What he is getting at is, if you capture the wood between nuts on the end of the threaded rod, you may have a problem with expansion/contraction.

Of course, some workbenches are produced exactly that way:

http://www.popularmechanics.com/home/how-to-plans/woodworking/4219723

.
Phil, I think those table tops are made with the cross grain up and down. Since wood moves across the grain, it shouldn't be much of a problem. For this table idea, I would guess it will not be flat in the summer if assembled in the winter. If a rustic design is wanted, that may not be a problem either. Perry

[Ryan Mooney]

I'd agree with Pat, there are really good odds of the bit wandering even if you start straight and true. Drilling from both sides is definitely the answer to that.

I built my workbench originally using this method, its about 24" across. The rods moved about 2 inches in the first year after which I pulled them out and plugged the holes (the top was also glued, I used the rods for alignment, "clamping" initially and left them in because it seemed like a good idea). If I was doing this I'd think about isolating each board on the rod so it can expand/contract independently. Probably by counter sinking a nut on each side (and castle nuts to cap the outside like Michael suggested even then because if the board shrinks the end can end up protruding as I found out to my chagrin), obviously there might be a better way to do the isolation... This will leave gaps in the top when they do move.. but avoids a lot of the other issues.

[Richard Coers]

I'm pretty sure there will be no controversy with the law of nature that wood expands and contracts. Phil? 48" wide, flat sawn douglas fir, will expand about an 1/8" for every one percent of moisture change. http://www.popularwoodworking.com/tricks/how-to-calculate-wood-shrinkage-and-expansion
Any idea of the current moisture content of the wood? If it is wet, you'll need a way to constantly tighten the nuts all winter. Then next summer, it will likely expand about 3/8" when the humidity rises. The nuts and washers on the rods will crush fibers in the wood and when the wood shrinks new winter, you'll tighten the nuts even more. If the fiber is strong enough to hold, maybe because of big washers, the table will bow dramatically. Steel and wood movement almost never play well together!

[Roy Harding]

Unless there's an over riding reason for using a solid piece of lumber - why not use two pieces of wood of half the thickness required. Run a dado down the length of both, then laminate them. Voila - square hole, straight, no need to align holes from both ends.

This doesn't address the expansion/contraction issue, but does answer your original question.

[Phil Thien]

I'm pretty sure there will be no controversy with the law of nature that wood expands and contracts. Phil? 48" wide, flat sawn douglas fir, will expand about an 1/8" for every one percent of moisture change. http://www.popularwoodworking.com/tricks/how-to-calculate-wood-shrinkage-and-expansion
Any idea of the current moisture content of the wood? If it is wet, you'll need a way to constantly tighten the nuts all winter. Then next summer, it will likely expand about 3/8" when the humidity rises. The nuts and washers on the rods will crush fibers in the wood and when the wood shrinks new winter, you'll tighten the nuts even more. If the fiber is strong enough to hold, maybe because of big washers, the table will bow dramatically. Steel and wood movement almost never play well together!

I'm right there with you, I think 3/8" might even be a little low.

[Michael Dunn]

I'm pretty sure there will be no controversy with the law of nature that wood expands and contracts. Phil? 48" wide, flat sawn douglas fir, will expand about an 1/8" for every one percent of moisture change. http://www.popularwoodworking.com/tricks/how-to-calculate-wood-shrinkage-and-expansion Any idea of the current moisture content of the wood? If it is wet, you'll need a way to constantly tighten the nuts all winter. Then next summer, it will likely expand about 3/8" when the humidity rises. The nuts and washers on the rods will crush fibers in the wood and when the wood shrinks new winter, you'll tighten the nuts even more. If the fiber is strong enough to hold, maybe because of big washers, the table will bow dramatically. Steel and wood movement almost never play well together!

I have a moisture meter I'll bring when I drop off the other pieces I've built for him.

[Michael Dunn]

Unless there's an over riding reason for using a solid piece of lumber - why not use two pieces of wood of half the thickness required. Run a dado down the length of both, then laminate them. Voila - square hole, straight, no need to align holes from both ends. This doesn't address the expansion/contraction issue, but does answer your original question.

The client has chosen and purchased himself, three large (4x12x100) DF boards. He wants these boards 'as is'. He does not want them 'cleaned up', by jointing, ripping, and/or planing. He also does not want the table to be flat or nearly flat. Kind of like an old pic of bench that has been weathered in the elements for years.

[Michael Dunn]

so, if you considered that movement, did you come up with a solution? i'd hate to see this guy's wood split or check in the spring when all of a sudden the humidity changes. and there are plenty of ways to build a 'rustic' table with (or without) edge gluing that would accommodate for wood movement... profile corners before gluing, scraping the top, or, maybe easiest, build your base so each board is attached with a fastener that allows for movement...you could find some way to incorporate the 'industrial' look in a way that does not involve the construction method. edit: oops mixed up my seasons...not as likely that wood will split upon expansion...but if the rods were tightened way down when the expansion occurred, maybe that could do it.

I was thinking I could insert the threaded rod once the holes have been drilled, put large (maybe fender washers) on, then nylon lock nuts, but leave a considerable gap for the inevitable expansion, then drill larger than necessary holes in the mounting cleat to allow each board to shift with the change in moisture. This way the boards will be securely held down, but allowed to move laterally when needed.

[Ethan Melad]

that sounds like it would work, so the rod basically just helps with alignment and aesthetics. if each board is attached to the base/cleat from the bottom, it doesn't seem like you really need the rod at all, though. might as well just screw something in from the edges in to create the industrial effect of the bolts?

[Michael Dunn]

that sounds like it would work, so the rod basically just helps with alignment and aesthetics. if each board is attached to the base/cleat from the bottom, it doesn't seem like you really need the rod at all, though. might as well just screw something in from the edges in to create the industrial effect of the bolts?

Correct, the rods are primarily for aesthetics. I guess to simplify I could get some hanger bolts. Drive the wood threads in however far they need to go to allow for the desired machine thread, washer & nut reveal.

[Phil Thien]

Correct, the rods are primarily for aesthetics. I guess to simplify I could get some hanger bolts. Drive the wood threads in however far they need to go to allow for the desired machine thread, washer & nut reveal.

Square nuts in black-oxide would look pretty nice.

[Mark Bolton]

Nice to see you boning up on the fundamentals but it still didn't catch the threaded rod til.... ;-)

The faux rods/bolts would be my route unless for some reason you or he is dead set on the rod. If that were the case you could always forstner your washer counterbores deep and put the largest wire size compression spring you could find behind the washers. This would keep the rods tensioning the table ( though likey never enough to keep it tight) and allow for movement. Plus they would neve be dangling in the holes which will inevitably happen.

Working for you is that shrinkage calculators call out 48" of flat sawn d fir at about .26" for every 2% when your below 10.

I would imagine if it were much more than that and you trapped the top with the rod the top would cup or other funk factor in time.

[Mark Bolton]

Yes, I know. Wood expands and contracts with the change in moisture. I read that in book on 'woodworking fundamentals'. After I glued and nailed the squaring blocks I realized I should've butted the end grain up against the guide block with the guide hole.

Or is there something else?

Can you explain what you meant here? Not following?

[Michael Dunn]

Can you explain what you meant here? Not following?

I thought he was referring to some aspect of the drilling jig I posted here. I figured since that's what I started the thread with that he was commenting on the jig. I glued and brad nailed some jointed and ripped 2x4's. I put the edge grain facing the workpiece where it is most likely to expand and contract. I should've put the end grain up against it as wood doesn't move much, if at all, in this direction.

I mentioned this earlier in the thread.

[Michael Dunn]

Nice to see you boning up on the fundamentals but it still didn't catch the threaded rod til.... ;-) The faux rods/bolts would be my route unless for some reason you or he is dead set on the rod. If that were the case you could always forstner your washer counterbores deep and put the largest wire size compression spring you could find behind the washers. This would keep the rods tensioning the table ( though likey never enough to keep it tight) and allow for movement. Plus they would neve be dangling in the holes which will inevitably happen. Working for you is that shrinkage calculators call out 48" of flat sawn d fir at about .26" for every 2% when your below 10. I would imagine if it were much more than that and you trapped the top with the rod the top would cup or other funk factor in time.

Yes. He's dead set on the rods with nuts. The updated drawing shows the recessed forstner holes. Good idea with the springs.

[Andrew Joiner]

Yes. He's dead set on the rods with nuts. The updated drawing shows the recessed forstner holes. Good idea with the springs.

So the customer really wants the rough fir? I hope he's dead set on getting slivers.

[Michael Dunn]

So the customer really wants the rough fir? I hope he's dead set on getting slivers.

Yes. That is what he wants. Exactly as it sits in his dining room right now.

[Andrew Hughes]

I had a cat once that had rough fur, turned out to be a porcupine.:eek:

[Mark Bolton]

I thought he was referring to some aspect of the drilling jig

Right, that's what I thought. Just making sure. ;-)

[Michael Dunn]

So he ended up deciding to have me sand and stain the table and bench. The drilling jig worked... Ok. Not great, but it got the job done. I didn't have time to find and buy and sort of steel guide bushing to slip in the hole.

[Chris Fournier]

Is it the photo perspective or are those threaded rods not centred from end to end?

[Richard Coers]

I thought you had to do the job in his condo? What happened to the stain in that one place on the table top? You can see a pretty distinct line that goes cross grain on the boards.

[Michael Dunn]

Is it the photo perspective or are those threaded rods not centred from end to end?

It's photo perspective. Although, equidistant would be the 'proper' term... ;)

100" overall length, 25" apart.

[Michael Dunn]

I thought you had to do the job in his condo? What happened to the stain in that one place on the table top? You can see a pretty distinct line that goes cross grain on the boards.

Which photo? I don't see what you're referring to.

Previously I decided to do the drilling of the holes in his condo. Then he decided to have me do the staining. At first he was going to do some strange DIY type stain idea invoking tea and some silly DIY channel crap. He asked me for advice. I didn't know of any ways to achieve the 'worn out' 'rustic' look. Now that he decided for me to do the staining I certainly didn't want to make several trips. I did all the work in my shop.

The hole drilling went pretty well. The jig I built helped. It's not perfect. The holes did end up wandering about 1/2" (at most, and only on one hole. The others were about 3/16" off edge to edge.) I was able to widen them enough though.

I drilled the forstner holes prior to drilling the 1/2" through holes. Then I put the second board against the first board to make starting mark. Repeat for the third board. I then used the Rockler cup hinge drill guide to do the forstner holes on the exit side. This allowed me to drill it without having a center point to start from since the through hole was already there.

[Ethan Melad]

So you did end up actually using a threaded rod and nuts on the ends? How did you account for the movement of the top?

[Mark Bolton]

Michael, Michael, Michael.. I sincerely hope you learned from this one..

[Richard Coers]

Which photo? I don't see what you're referring to.

.

Next to the last photo. About a third of the way up from the near end. It shows as a slight v in the two boards to the right, and maybe extends into the 3rd board. It shows near the top of the 3rd photo from the bottom, on the left two boards.

[Michael Dunn]

So you did end up actually using a threaded rod and nuts on the ends? How did you account for the movement of the top?

The threaded rods are in place for aesthetics. I used washers as well. Medium strength thread lock to hold the nuts in place as I did not tighten them. Then, to fasten the top to the base I drilled oversized holes in the base to give it some room to move.

FWIW, I measured the moisture content and they were all around 10-10.5% compare to the usual 6-8% for non construction grade type lumber. Someone said that this type of lumber typically has around 18% or something like that.

When I deliver the table I plan to loosen the fastening bolts a bit. This table is so big and so heavy that it barely even needs fastening. Barely. Not that I would ever do such a thing. I'm just saying that it can surely be given some more room to move and breath with the change in moisture.

[Michael Dunn]

Next to the last photo. About a third of the way up from the near end. It shows as a slight v in the two boards to the right, and maybe extends into the 3rd board. It shows near the top of the 3rd photo from the bottom, on the left two boards.

This pic? I'll have to compare it to the actual table to see if its a photo/lighting issue.

[Chris Fournier]

It's photo perspective. Although, equidistant would be the 'proper' term... ;)

100" overall length, 25" apart.

I'd be interested to see a tape measure on the table show me equidistant. I know that poor photography is deceptive but this instance is pretty exaggerated! I can see that the forstner holes in the last image are not stained.

Personally I'd have installed something closer to the ends, say like 6" to 8" away. If the rods are placed as you say they are you have essentially 50" (outside rod to end of table X 2) of table top free to do what it may. Not a terribly great set up for all of the trouble.

[Michael Dunn]

Michael, Michael, Michael.. I sincerely hope you learned from this one..

I like the idea with the springs. I'm going to do that.

[Richard Coers]

Yup, that one. Looks like the wood might have been exposed to light or the sun, and part of them had something stacked on it. Maybe you didn't sand them very hard? Looks like it might show up harder when it gets a clear coat.

[Michael Dunn]

Michael, Michael, Michael.. I sincerely hope you learned from this one..

For the record, the staining was done for an extra charge above the previously agreed upon amount.

[Michael Dunn]

I'd be interested to see a tape measure on the table show me equidistant. I know that poor photography is deceptive but this instance is pretty exaggerated! I can see that the forstner holes in the last image are not stained. Personally I'd have installed something closer to the ends, say like 6" to 8" away. If the rods are placed as you say they are you have essentially 50" (outside rod to end of table X 2) of table top free to do what it may. Not a terribly great set up for all of the trouble.

So which is it? Is it bad to lock these boards together or not? Geeze... It's a bit early (or late...) for April fools!!! Like I said, the threaded rods are there for aesthetics and are not tight enough to restrict movement due to change in moisture.

So adding 2 more rods and the accompanying 6 holes would be more time and labor. Yesterday my client suggested the same thing. I told him I'd have to charge him extra, he declined.

The entire 100" length is free to do as it may.

Here's the pics to show the placement of the rod holes. Not dead on 25" apart, but close enough to the eye.

As for the staining issue, I can't say its a sanding issue... The boards are all sanded to the same grit, at the same rate, for the same amount of time. Perhaps I rubbed too hard when wiping the excess. This was the first coat. In fact I think the entire mid section of each board is considerably lighter than the outer sections.

[Mark Bolton]

For the record, the staining was done for an extra charge above the previously agreed upon amount.

Oh, of course, that would be a given.

[Chris Fournier]

If these threaded rods are only for aesthetics why bother through boring at all? It would have been far easier to cut short sections of all thread, loctite on a nut, slip on a washer and simply glue this falsey into a shallow hole. No drama, no hassle, no complications.

[Michael Dunn]

If these threaded rods are only for aesthetics why bother through boring at all? It would have been far easier to cut short sections of all thread, loctite on a nut, slip on a washer and simply glue this falsey into a shallow hole. No drama, no hassle, no complications.

Agreed, but he was dead set on it. Rather than go through all the details (of this thread) I just went ahead and did it his way. Partly just to avoid explaining it all, and partly because I had already purchased the threaded rods and built the drilling jig prior to starting this thread and someone suggesting that. I suppose I couldn't just done it anyway. However, then I'd feel like I was lying to him as it was not what we agreed upon. It's done, and it didn't take all that long either.

[J.R. Rutter]

The table looks good. I personally like the look of the exposed nuts. A stack of rubber washers under the washers on each side would help absorb any movement. Even though it can theoretically move a lot seasonally, with the thickness of the timbers odds are it won't be extreme.

[Mark Bolton]

odds are it won't be extreme.

Agree completely. The table simply being so rough/rustic alone and leaving gaps between the timbers would negate any trapping of the top in any way (rods, battens, whatever).

I think the point has been the same as with most of these posts. A statement/question is posted which lacks the vast majority of the details. In this case, a conversation happened with a paying customer with regards to trapping a wide top with threaded rod. A super basic no no. The conversation likely should have ended right there with a bit of customer education either by informing them that this may likely cause failure of the top, or the work around (springs/rubber washer/faux bolts) would cost more.

I can only assume the conversation may have ended there (with a cost increase)

At least to me, upon reading the initial question, it would be hard for any reader to think the customer was asking someone to build a high priced picnic table (which is basically what this is, and no offense to Michael as it seems he built what the customer wanted).

You hear the materials, and "table", and you think something conventionally joined, built with the intent, and common convention, of indoor furniture.