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planing wedge and dogs system

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Forum topic by AaronK posted 1752 days ago 1356 views 0 times favorited 8 replies Add to Favorites Watch
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AaronK

1389 posts in 2068 days


1752 days ago

Topic tags/keywords: jig question clamp

inspired by this and something i read in The Workbench Book by landis, i am trying to design a planing wedge to work on my bench. I came up with:

wedge

the basic idea is a 15º pitch over several inches of “clamping” area. I want to use it for surface and edge planing for thick and thin materials. the dogs are rectangles with dowels through them… so they can be rotated and easily fit into an existing bench top but dont fall through and provide a flat clamping surface.

any ideas for improvements before i begin?


8 replies so far

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a1Jim

112001 posts in 2181 days


#1 posted 1752 days ago

cool

-- http://artisticwoodstudio.com Custom furniture

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Bud

45 posts in 1889 days


#2 posted 1750 days ago

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ondablade

105 posts in 1802 days


#3 posted 1750 days ago

Hi Aaron, i’m planning a bench right now and thinking of going for square headed 3/4 hardwood dowel dogs too – the metal variety sound expensive and risky for blades, and square ones are surely limited by the fact that they can’t rotate to handle angled work. You can also do versions if needed with all sorts of head shapes for special situations.

The one (theoretical as i’ve not used them) uncertainty with this type of dog to my mind is whether or not a simple round dowel with a clearance fit in a vertical hole might not be inclined to work it’s way up out of the hole in use – if only by a small amount. I thought of angling the sides of the dog heads or holes, but decided it would be restrictive.

Does anybody know?

The fancy metal and square ones you see in the books have some sort of clip and cross hatching on on them, although it’s hard to see it doing much.

The wedging principle seems like it should work, but unless you know better maybe some experimentation to determine the best angle might be worthwhile – i guess it’d be nice if the ramp was fine enough so that the the clamping action would lock up tight – so that a tap of a mallet was needed to loosen it. (the wedge would need a good strong return leg at its end to take this and working loads without damage)

I presume the rectangular slip you have is a combination packer piece for width setting and a protective pad for the work.

FWW have a link to a bench design on their home page using a simpler wedging arrangement to hold pieces on edge for planing on the bench top, although it looked to me like the ‘V’ it uses might damage a workpiece edge.

Two other options i’ve seen around recently for planing edges on work are (a) a large woodscrew to hold the workpiece clamped to the bench top, and (b) an adjustable height edge support rail mounted across the legs to the front of a bench so that e.g. a door panel resting on it can be held in a front vice to the LH end.

Not sure if you plan more holes than you show in the sketch, but the other issue i’ve been playing with is layout of the grid for the dog holes on the top surface of the bench. It needs to be oriented square to and aligned with any dog holes you have for clamping frames/panel etc in the top of the moving jaw of the head and tail vices, and on an appropriate spacing so you don’t get caught unable to handle certain widths without packing pieces. (i guess this in your case depends a bit on the ‘lift’ that works on your wedge)

ian

-- Late awakener....

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AaronK

1389 posts in 2068 days


#4 posted 1750 days ago

hey ian:

lots of stuff! i’ll go in order…

cant comment on the dogs other than to say i’m not too concerned about their geometry yet! capping round ones with a rectangular top seems like a good compromise.

the 15º pitch came from literature, so i’d imagine it works well enough. it’ll be easy enough to change by manipulating the geometry of the wedge itself.

the rectangular piece is just for what you say :-)

i have seen simpler wedge designs that simply trap the workpiece within a V shape – but it seems only suitable for edge work or else really narrow stock.

with regard to the other options, (a) doesnt appeal to me cuz i want nothing protruding above the work surface and (b) well, i dont have a good face vice system yet.

finally, the grid of dog holes actualy IS square to the long side of the bench. i understand what you mean about widths, but these can be overcome by using dogs with larger “tops” – or even easier, by using dog tops that non-symmetric, so they can be rotated for the best fitting side.

anyway, thanks for all the comments. I basically had really similar concerns and was wondering if this design (it’s only about 10% mine) would address them… and i think it does. It does seem flexible enough so anything that doesnt work so well can be adjusted or fixed.

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ondablade

105 posts in 1802 days


#5 posted 1749 days ago

Sounds good Aaron. The one definite you can be sure of is that you’ll find you’ve overlooked stuff when you planned it. Maybe the best we can hope for is that we start with something that at least won’t block evolution/problem solving.

Re. my caution about the possibility of the dogs lifting. (this for my own benefit :-)) Have you seen square headed round dogs in use?

Alternatively please report in due course – it’d be good to hear how you get on…..

ian

-- Late awakener....

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AaronK

1389 posts in 2068 days


#6 posted 1749 days ago

I haven’t seen these type of dogs in use. I’ve turned them around in my head wondering how they’ll respond to eccentric forces and I’m not 100% sure about them – especially if they are themselves non-symmetric. In fact, the only thing i seriously modified from the pictures i saw in the book was the use of dogs as supports instead of beams mounted in two dog holes (does that make sense?) – which couldve been done because dogs would rotate. easy enough to modify afterward, and i’ll be able to use these fancy dogs elsewhere if thats the case.

i’ll report back once i’ve done it.

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AaronK

1389 posts in 2068 days


#7 posted 1744 days ago

UPDATE:

I made it and it works better than i thought it would. i didn’t do it entirely as planned. i changed the spacing of the dog holes to make them 4” apart (when i started drilling, 2” seemed WAY overkill). also i didnt make individual dogs, just used some scrap strips of ply with 2 dogs in each. i was too lazy to make 4 dogs and it also seems like it might be more secure this way. also, i increased the size of the wedge, and consequently, i dont need the lower wedge strip. finally i finessed the dimensions to be a little easier to get right (ie, no 64ths).

i has a little trouble getting a completely smooth miter on the wedge using my TS (craftsman, lol), but it works just fine even with a non-straight edge. the workpiece becomes trapped very quickly and solidly for hand work and is released with a quite gentle tap to the front of the wedge. even edge jointing is stable. the only thing limiting me now is the (short!) length of my bench…

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ondablade

105 posts in 1802 days


#8 posted 1744 days ago

Sounds like 15 deg is the magic angle??

ian

-- Late awakener....

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