Need advise on size of twin screw chop

[Paul Erickson]

I am trying to decide how large to make the twin screw chop on my new bench. I am figuring that 18" between screws should be sufficient for the majority of the work I will do, and due to the bench design have other options for those rare occasions when I need to clamp a larger piece. I could go with 24" but feel that the additional size would unnecessarily take up space and be a bit more awkward for general use.

Here is a mock-up. The green tape indicates where the chops will likely be cut. As shown, the chop will accommodate about 20" board, but I think it is a bit too large. The 2x6 in the middle will be an experimental movable jack.



DSCN3199.jpg


Any suggestions will be appreciated.

cheers, Paul

[Dave Anderson NH]

My twin screw is used as a face vise and has wooden screws. I have 24.5" between the screws so that I can put a carcass piece between then without difficulty. I have not found it awkward at all, but my bench is 90" long

[Paul Erickson]

My twin screw is used as a face vise and has wooden screws. I have 24.5" between the screws so that I can put a carcass piece between then without difficulty. I have not found it awkward at all, but my bench is 90" long

Hi Dave,

Thanks for the reply. I like the idea of being able to hold a carcass piece in the vise, but you have a bit more room than I do. . .Interesting thought, will have to think
about it.

cheers, Paul

[Joe A Faulkner]

My twin screw is used as a face vise and has wooden screws. I have 24.5" between the screws so that I can put a carcass piece between then without difficulty. I have not found it awkward at all, but my bench is 90" long

Dave, I'm curious as to how you like the 90" length. What led you to this length? To date, my projects have essentially been pieces for the house - kitchen cabinets, book shelves, beds. Only recently have I started using handtools and to date haven't really had a true workbench. I'm in the planning stages for one and am thinking somewhere between 7' to 8' in length. Most benches seem to be in the 7' range. Did you grow into the 90" length (bench upgrades) or was there something else about your work that motivated the longer bench? I keep thinking that I'm over thinking the length and should just go with 7' and get on with it.

I'm also leaning towards a twin screw face vise with 24" centers.

[Dave Anderson NH]

Hi Joe,
When I built my new bench 3 or so years ago I glued up the top at 97" from the jointed and planed rough stock lengths. After placing it on the completed base in the spot where it would live it became apparent I would not have adequate room to move around it on all 4 sides without squeezing past my sharpening bench at one end and a support pole at the other end. I clamped a straightedge guide on the top and cut off the 7" with a circular saw. My original bench had been 28" x 72" and was wider than needed and I found it too short. It is now my assembly, finishing, and metal working bench. I use the new bench for all my woodworking including the sticking of moldings with molding planes. I find the extra length also allows me to stage parts of a project at one end and still have enough room to actually work. Like many here I do not have a tool tray.

[michael osadchuk]

My workbench is 10 feet long and I've never regretted the length...... with a long bench I can easily accommodate two projects or two stages of a projects simultaneously on the bench. I also the the length to act as flat reference surface when milling long pieces of rough sawn lumber to see what is not flat, straight. I agree with Dave that a bench can be too wide.

If you have the space......

good luck

michael

[Paul Erickson]

Dave,

Thanks for the thoughts and picture. Any chance of seeing a picture of your twin screw vise?

cheers, Paul

[Bob Jones]

I agree with Dave. I have a Moxon style twin wooden screw vise with just over 24 in between screws. It sure was nice to have when I made a chest recently. It is still easy enough to use for smaller boards. I highly recommend the removable Moxon style vise. Chris S. has blogged alot about it, so research should be easy.

[Dave Anderson NH]

Paul, I'll post one this evening when I get home from the day job.

[Dave Anderson NH]

Sorry for the late post of the twin screw vise Paul.

[ian maybury]

Bear in mind that this is not from the perspective of heavy user experience, but I'm mid build on a Roubo, and went the other way.

The original plan was a Twin Screw Veritas at the LH end as a face vise, but when drawn to scale on what will be a 90in bench it just seemed to take up too much territory. Plus mounting the fixed jaw involved either a cut out in the bench top, or jointing its top edge to the underside - all of which also complicates the leg layout and isn't structurally ideal. The jaw depth is limited by the screws unless you run with deep jaws that may bring tipping problems.

I'm installing the Twin Screw vertically as a leg vise, it fits in nicely. I've not seen it done, but think with a few tweaks to improve the support of the top screw to reduce slop it will be fine. As Bob there's a fairly widely held view that a Moxon style vise is a more flexible solution for holding wide parts - it's removability makes it very flexible.

The only real loss I can see in going to a leg vise is that you lose the availability of a long jaw top to take dog holes - if for example you want to use it to clamp up frames on the bench top. It seems to me that there are probably ways around that though....

ian

[Joe A Faulkner]

Great looking Bench Dave, from both sides!
Looks like your legs are flush on the twin-screw side. I notice you have a stretcher across the tops of the legs as well. How is the top connected to the base?
How thick is your bench top and what species? Ash?
Do you find yourself using the deadman much? Schwarz's second workbench design book, in the chapter on the Hotlzapffel workbench, he decided to leave the deadman off noting that between the work holding he could accomodate using clamps on the far leg and holding strength of the double screw vise, he didn't think he needed it. I'm curious how this worked out for you?

[Dave Anderson NH]

The bench top is ash 3" thick. The 2 leg assemblies have top stretchers with 3/4" diameter oak "bullet tenons" drilled into them and sticking up about 1". The bullets engage holes drilled into the bottom side of the top, 2 are round and 2 are slightly elongated in case there is any wood movement. After the top was in place I decided to add one ong lag screw up through the upper stretcher and into the top so that the bench could be moved by grabbing the top and lifting.

I rarely use the deadman since most long stock I clamp in the twin screw vise is narrow. I find a round dog stuck into one of the holes in the legs usally is faster and easier. Often nothing is used since the jaws of the twin screw are 34.5" long.

[Paul Erickson]

Sorry for the late post of the twin screw vise Paul.

No problem Dave, thanks very much.

cheers, Paul

[john brenton]

With a small bench like that, I wonder what would happen if you made the chop the full length of it? Not only could it be useful for panel glue ups, but it would work to make your bench wider when extended.

Just a thought...kind of a weird one, but I can't think of any real drawbacks.