Workbench Design questions

[RiverWalker]

May 9, 2010 13:04:02 GMT -6 dcarter636 said:

I'm not into sketch-up so I'll try with verbiage.

I would reduce the top stretcher tenon to 1"x2" so that it doesn't break through the shoulder of the benchtop registration tenon on the top end of the vise leg. Center it on the leg to keep the loading symmetrical and because it's simpler to lay out.

I would also reduce the benchtop registration tenon to 1 ¹/₂"x3" (that's almost a 2x4), which is plenty strong without compromising so much of the of the benchtop edge strength.

Also once you have properly laminated those boards with Tite Bond II, III, or the equivalent think of them as homogeneous wood, don't worry about where the glue joints were when laying out your joint features.

Big tenons and overly strong joints are fine things, but keep in mind that the forces that would challenge M&T joints half the size that you show here will tip this 2'x4' bench up on end.

Pretty sure I follow what you mean, that'll be in my next posted version for further advice. are other joints severely overkill such that it'd be easier and just as effective to do them differently?

how far does that titebond stuff go? I mean, what size of bottle would probably be neccessary for the laminations and construction? (they seem to come in 4, 8, 16, 32oz, 1 gallon sizes..)

also, in the kirby workbench design in the workbench book, it has a gap between where the top rests on the stretchers, and the top of the legs it depicts that as a way to prevent seasonal moisture variation from causing the leg structure to warp the top.
... is that actually a serious issue, or is that overly cautious and/or for locales that have especially high seasonal humidity variations?

[Safetyboy]

May 9, 2010 11:19:06 GMT -6 RiverWalker said:

now I have a particular point I'm hung up on that I'd like opinions on

the joint between the upper stretcher on the left side, and the vice-leg.

If you're gonna mortice the legs into the top, I don't think you need the upper stretchers there at all...

[dcarter636]

We used to buy the original TiteBond in gallon jugs. As our stock preparation and clamping rituals improved we bought TBII in quarts. Our joinery fitting has improved to where now I may use a couple pints of TBIII per year. Without a jointer and thickness planer you may use more than a pint of TiteBond in making the legs and top for this bench. Better to need to buy a second pint than have a half used quart sitting around going stale.

"...it has a gap between where the top rests on the stretchers, and the top of the legs it depicts that as a way to prevent seasonal moisture variation from causing the leg structure to warp the top."

I'm not 100% certain of your meaning but I think the top should stiff enough to cause the legs to conform to it. If the top rests on the top ends of the legs and the upper stretcher is a tad lower, then a single 5/16" screw or lag bolt through the mid point of each stretcher would encourage the legs to stay in contact with the top. That is what I did with the quickie construction lumber bench that I posted earlier here.
I have some doubt about the resistance to long-wise racking absent a upper long stretcher or diagonal brace, but that can be addressed later if it appears necessary.

[sawduster]

I think I'm agreeing with Dave on this, but I would make the shoulder on the tenon piece at least 1/2" wide. This will increase the resistance to racking. I would center the mortises on the legs.

An added benefit of that is that you could then use dimensional lumber as a filler if you were to later add an end vise or an adjustable planing stop like I've got on mine. If you look at the second picture I posted showing the material holding, you can see the planing stop held in place at the end by 2 jig knobs (you can only see the one) and two 1/4" bolts. If you look real close you can see that there is an "L" shaped slot cut through the stop allowing it to be raised and lowered as well as slid to the side to be use in conjunction with the leg vise. To that end I would widen the shoulder of the tenon going into the top on the outboard side to the 1 1/2" thickness of you 2 X 4 material.

[RiverWalker]

May 9, 2010 20:26:01 GMT -6 Safetyboy said:

If you're gonna mortice the legs into the top, I don't think you need the upper stretchers there at all...

oh, no no, only the vice-leg is morticed to the top.

see, I'm kinda cobbling together relevant features from a variety of the benches discussed in the workbench book.

the overall base design, I'm starting with the kirby bench, the leg vice-top part is from the Roubo bench, the sled-foot part is sorta in like 2 of the other designs.

if all the legs were morticed to the top, yeah, then wouldn't have that stretcher at all.

Dave, initially I would have thought so on the long-stretcher too, but the kirby bench only has the lower long-stretcher too, I think that the way it has pieces attached to the ends of the lower stretcher to double the length of the tenon is supposed to help with that.

on the thing about the gap witht he top and the stretcher, it had it so that like, there was a bridle joint(I think thats what its called) between the upper stretcher and the legs, and they had it so that the top surface (that the benchtop would rest on) would rest in its mortice, so that the very end/top of the leg material would not directly contact the underside of the benchtop.
they fastened the top to the stretcher(only, not to the legs directly) with bolts nuts and washers, through slightly oversized holes .
none of the other benches they discussed seemed to have such concern in this direction.... and it doesn't sound like an important secret or anything. so I won't worry about it.


Jerry, you mean the shoulder on the tenon of the long-stretcher, or the tenons in general?




I think I follow much of what you guys are saying, and will incorporate that.

off to refine it more!

[sawduster]

Basically, on all mortise and tenon joints. With M & Ts you need to do a balancing act. Lots of folks assume that the tenon is the key to the strength of the joint, but the mortise is equally responsible; the thickness of the walls of the mortise need to be up to the task. The tenon, because of its orientation to the grain of the wood has tremendous strength in the directions to which force will be applied to the joint in the use of the piece, while those same forces can easily split the grain on the sides of the mortise as well as the shoulder between the top or bottom of the mortise and the end of the mortise piece. Bigger shoulders add thickness to the walls of the mortise, adding to it's strength.

With the bench as you have designed it, splitting out the mortise walls is secondary, though, to the added strength the shoulders provide against racking. Pinning or draw boring the tenons would add further assurance against racking.

Guess I've gotten off on a tangent, which I have a tendency to do. Sorry about that. But it is good to have as much information and as many ideas when in the design stage of things.

Your mention of using what you liked from several benches in the book is a good idea. That's what I did when I built my first router fence set-up. Scanned back through magazines and such picking out what I wanted from several and incorporating them while designing my own rather than using someone else's overall plan.

Another option is to start off with a very basic bench, working with it, and modifying and adding stuff that you find that you really need.

[RiverWalker]

May 10, 2010 10:22:08 GMT -6 sawduster said:

Basically, on all mortise and tenon joints. With M & Ts you need to do a balancing act. Lots of folks assume that the tenon is the key to the strength of the joint, but the mortise is equally responsible; the thickness of the walls of the mortise need to be up to the task. The tenon, because of its orientation to the grain of the wood has tremendous strength in the directions to which force will be applied to the joint in the use of the piece, while those same forces can easily split the grain on the sides of the mortise as well as the shoulder between the top or bottom of the mortise and the end of the mortise piece. Bigger shoulders add thickness to the walls of the mortise, adding to it's strength.

With the bench as you have designed it, splitting out the mortise walls is secondary, though, to the added strength the shoulders provide against racking. Pinning or draw boring the tenons would add further assurance against racking.

Guess I've gotten off on a tangent, which I have a tendency to do. Sorry about that. But it is good to have as much information and as many ideas when in the design stage of things.

I don't think thats a tangent at all, lol, in fact its precisely the sort of thing I want to know and that makes a big difference. when you say it like that, that totally makes sense, but it hadn't occured to me like that, and its extremely helpful and well-explained.

in another day or two I should have another version and more questions to share and get advice on.

[dcarter636]

I think you have a pretty decent overall design there, witnessed by the fact that most of us are commenting primarily on details. A post end bridle joint is simpler to make than M&T which is stronger, but it's probably not all that critical here.

Unsolicited philosophical comment:
Building something like this can offer constructive learning experience at every turning, sometimes the best lessons are in how to recover from a misstep, but it is all constructive.
Many of us use these projects to experiment with new methods, processes, finishes, or materials. Sometimes you can end up with better furniture in your shop than most folks have in their living rooms, and sometimes you'll make very expensive firewood, but you will learn something useful and progress as a wood worker every time you attempt something new.

[sawduster]

Unsolicited philosophical comment:
Building something like this can offer constructive learning experience at every turning, sometimes the best lessons are in how to recover from a misstep, but it is all constructive.
Many of us use these projects to experiment with new methods, processes, finishes, or materials. Sometimes you can end up with better furniture in your shop than most folks have in their living rooms, and sometimes you'll make very expensive firewood, but you will learn something useful and progress as a wood worker every time you attempt something new.

Wow, that just brings a tear to my eye, Dave. ;D Great comment!!!

[RiverWalker]

Dave, much appriciated, with that in mind I added some variety to the design to get experience and such with different things.

I'm still kinda finicky and insecure though, lol, so heres my newest revision:

most M&T's moved to half inch shoulders, and shortened to not be through.

figuring to drawbore most of it.

added dowels, dovetails, end caps on the top, added dogholes. adjusted a few things, and added an apron on the left half of the benchtop. (to facilitate clamping to the bench on the same plane as the vice, for dovetailing wider pieces and such. extending it to the left side as well, seemed stylistically preferable and maybe useful.

the dogholes are 3/4" square, one in the vice face, a row in line with the vice screw. others perpendicular to those to facilitate panel stops.
more dogholes on the right side to facilitate attachment of other things or other to-the-top clamping flexibility.

am I overdoing it on the dog holes?

the model also has the layout I'm figuring for getting all the pieces out of the lumber the most efficiently.

heres the 3d Warehouse link:
sketchup.google.com/3dwarehouse/details?mid=e8841244e82073086c6cbf2e5e03b43d

heres a screenshot, not sure it helps much though.



I am worried about wood movement making things go screwy later on, I do hope to move within the next couple of years, but I'm not sure how much difference there is between southern illinois and southeast nebraska(the expected/hoped for destination) but it concerns me a little.

I am figuring from what I've read that a simple boiled linseed oil finish would be most suitable. once cured fully the oil finish wouldn't contaminate anything or whatever, right?

[dcarter636]

Not in any particular order:

Southern IL and SE NE are similar, weather wise. I-35 is the marginal boundary (+/-100 miles) between the western plains and eastern forests so environmental changes should be negligible.

That does look like a very nice and utilitarian bench, with lots of opportunities for skill development.

There is no such thing as too many dog holes IMO. I do get queasy about the stiffness of 3/4" wooden dogs but your 3/4" holes should accommodate most of the store bought metal bench furniture available. For hard wood dogs I prefer 1"x1¹/₂" plus a shoulder.

The end cap on the far end should be fitted via a sliding dovetail joint all the way across the full width of the bench. This is a very ambitious joint for a novice without a work bench, but a fantastic learning opportunity.

The near end cap appears to be captured and in conflict with the expansion/contraction of the laminated field of the bench top. An end cap needs to be somewhat free to change length at one or both ends or you will eventually suffer cracking or a joint failure.

I would eliminate the T1 piece and extend the T2 to full length. the wider T2 skirt has value for clamping and stabilizing long boards held horizontally in the leg vise. It will also add longitudinal rigidity to the bench top.
If you want to practice dovetail splices do it in the laminations where less than perfect is out of sight. You will know about the perfect joints even if no one else does, and you won't feel compelled to throw out the lumber with the less perfect joints.

Do you have the lumber yet?

[RiverWalker]

May 30, 2010 14:26:19 GMT -6 dcarter636 said:

Not in any particular order:

Southern IL and SE NE are similar, weather wise. I-35 is the marginal boundary (+/-100 miles) between the western plains and eastern forests so environmental changes should be negligible.

That does look like a very nice and utilitarian bench, with lots of opportunities for skill development.

There is no such thing as too many dog holes IMO. I do get queasy about the stiffness of 3/4" wooden dogs but your 3/4" holes should accommodate most of the store bought metal bench furniture available. For hard wood dogs I prefer 1"x1¹/₂" plus a shoulder.

The end cap on the far end should be fitted via a sliding dovetail joint all the way across the full width of the bench. This is a very ambitious joint for a novice without a work bench, but a fantastic learning opportunity.

heh, no no, I was only figuring to dovetail the front and rear laminations to the side pieces, but thats an interesting idea... I might have to consider that. in for a penny in for a pound on ambition maybe? lol

I'm not sure how to do the long slot portion though, with the very limited tool options I have/will have.

The near end cap appears to be captured and in conflict with the expansion/contraction of the laminated field of the bench top. An end cap needs to be somewhat free to change length at one or both ends or you will eventually suffer cracking or a joint failure.

I would eliminate the T1 piece and extend the T2 to full length. the wider T2 skirt has value for clamping and stabilizing long boards held horizontally in the leg vise. It will also add longitudinal rigidity to the bench top.

I think the way the labeling displayed for the screenshot made that confusing, but you are suggesting having the wider front lamination go all the way across the front of the bench, rather than only halfway? I was worried on that resulting in restricting options for being able to use clamps to fasten things to the top of the bench, but I wasn't sure if that was really an issue or not.

I was figuring the half-blind dovetail on the front left corner to keep a single wood face for the entire area near the vice.

other than a sliding dovetail or similar, what sort of fastening of the end pieces would be preferable? in that plan I had it doweled to the laminations every couple of them, but I am not sure if that would be a bad thing for expansion, or what. I hadn't originally intended to include end caps, so its not as developed.

If you want to practice dovetail splices do it in the laminations where less than perfect is out of sight. You will know about the perfect joints even if no one else does, and you won't feel compelled to throw out the lumber with the less perfect joints.

Do you have the lumber yet?

no, I haven't got it yet, which leads to another issue, how long should the wood be in the environment it'll be residing, before working it?

[dcarter636]

It might be better to delete the end caps from this bench top, they are going to be in conflict with the laminated field when seasonal humidity changes. Wood changes negligibly in the long grain direction (end caps) while the cross grain dimension (lams) will change measurably with the seasons. The reliable way to attach end caps is via some sort of free floating joinery with a single anchor point such as sliding dovetails, floating breadboard ends, or something similar with a single pin keeping things together. My first attempt at a small table top split hopelessly because the solidly attached breadboard ends constrained the expansion/contraction of the field boards. The end caps may bring more trouble than they are worth.

I think adding a couple narrow right angle brackets glued to the underside of the top to support an adjustable planing stop board like Jerry has on his bench would be more durable and useful than fixed or captured end caps.

"...how long should the wood be in the environment it'll be residing, before working it?"
If the lumber to be joined comes from the same stack or mill lot then a few weeks of acclimatization in a stickered stack is probably good enough. I recently had a practical lesson in this when I thickness planed some cherry boards at near zero RH and then last week at 40%-50% RH cut tenons on their ends.
My thickness planer reliably cuts a uniform thickness within .002" across 12" of width, four 1"x6" boards were run through it at the same thickness setting a couple months ago. The lumber had been in my possession for several weeks prior to thicknessing but had come from different mill runs and were not all exactly alike. Two of those boards are now tapered .025" across their width, that makes cutting tenons on their ends to a uniform thickness a PITA by conventional means and raises vexing questions about what thickness those tenons will become next winter. The other two boards remain a uniform thickness.
Acclimatization is an important detail, but not a guarantee of future uniformity or predictable seasonal movement.

"...but you are suggesting having the wider front lamination go all the way across the front of the bench, rather than only halfway? I was worried on that resulting in restricting options for being able to use clamps to fasten things to the top of the bench, but I wasn't sure if that was really an issue or not."
I like a 8"-10" wide edge on one side of the bench with staggered holes for work supports, and leave the other side thinner for vertical clamping. However my bench sits in the middle of the work area, permitting access to both sides and one end. I think this is more a personal preference than a vital design feature.

I've wandered a bit here, and it is late, so those are my thoughts at this hour.

[RiverWalker]

May 31, 2010 2:38:45 GMT -6 dcarter636 said:

It might be better to delete the end caps from this bench top, they are going to be in conflict with the laminated field when seasonal humidity changes. Wood changes negligibly in the long grain direction (end caps) while the cross grain dimension (lams) will change measurably with the seasons. The reliable way to attach end caps is via some sort of free floating joinery with a single anchor point such as sliding dovetails, floating breadboard ends, or something similar with a single pin keeping things together. My first attempt at a small table top split hopelessly because the solidly attached breadboard ends constrained the expansion/contraction of the field boards. The end caps may bring more trouble than they are worth.

I think adding a couple narrow right angle brackets glued to the underside of the top to support an adjustable planing stop board like Jerry has on his bench would be more durable and useful than fixed or captured end caps.

ok, I think I will take that advice and skip the endcaps.

I am not sure about the panel stop thing on the end, but I may see about that too.

that could be added on entirely later though, right? I might just see about using doghole-attached panel stops with the line of vice dogholes and then add that later if I really need that bit more length.

"...how long should the wood be in the environment it'll be residing, before working it?"
If the lumber to be joined comes from the same stack or mill lot then a few weeks of acclimatization in a stickered stack is probably good enough. I recently had a practical lesson in this when I thickness planed some cherry boards at near zero RH and then last week at 40%-50% RH cut tenons on their ends.
My thickness planer reliably cuts a uniform thickness within .002" across 12" of width, four 1"x6" boards were run through it at the same thickness setting a couple months ago. The lumber had been in my possession for several weeks prior to thicknessing but had come from different mill runs and were not all exactly alike. Two of those boards are now tapered .025" across their width, that makes cutting tenons on their ends to a uniform thickness a PITA by conventional means and raises vexing questions about what thickness those tenons will become next winter. The other two boards remain a uniform thickness.
Acclimatization is an important detail, but not a guarantee of future uniformity or predictable seasonal movement.

ok, the wait might suck, but I think that means I'll definitely have to get the wood as soon as I can. I am going to need to be able to cut at least some of the main crosscuts right away though, so I can fit it in the room available. but since moisture doesn't change length, that shouldn't be too much of a problem, right?

"...but you are suggesting having the wider front lamination go all the way across the front of the bench, rather than only halfway? I was worried on that resulting in restricting options for being able to use clamps to fasten things to the top of the bench, but I wasn't sure if that was really an issue or not."
I like a 8"-10" wide edge on one side of the bench with staggered holes for work supports, and leave the other side thinner for vertical clamping. However my bench sits in the middle of the work area, permitting access to both sides and one end. I think this is more a personal preference than a vital design feature.

I've wandered a bit here, and it is late, so those are my thoughts at this hour.

hmmm, well the plan I had on this last posting of it, had the very front lamination being 4.5" I think it was, thick(er, wide?) on the left side, and the main bench thickness(3") on the right side.

I am not figuring to have both sides of the bench acessible like yours, so having the full front being thicker would pretty much (except on the ends perhaps?) rule out vertical clamping like that.

anyway, a little more to tweak then. and I'm open to more advice otherwise too.