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fixerdave
05-22-2008, 04:13 AM
Hi,

I'm looking for some design-advice on a panel saw I'm making. Basically, the current iteration of the design has a 1/2" steel pin that goes through a support post. Two pins actually, one above and the other below the vertically-held panel I'm cutting. These pins are mounted to a saw guide and hold it in alignment with the support post.

I'd like some kind of clamp on the back side of the support post that both quickly pulls the pin tight to clamp the guide against the panel and then holds it in place. The guide, with pins, must be quickly removable as well. The clamp mechanism can be permanently mounted to the back of the support post.

I'm thinking of some kind of friction-cam that rolls up against the side of the pin for a 1/4 turn, pulling it tight, and then locks itself in place. One complicating factor is that the panels will vary in thickness so the clamp will have to adjust to this. It doesn't, however, have to hold that strong. I would like the locking operation to be one-handed, quick, and not involve a whole lot of fiddling around. I mean, I could just thread the rod and spin a nut on, but I'm trying to avoid that.

The problem is that I'm having a hard time visualising the cam and, more importantly, how to make it. Okay, that's two problems, three if you count that I'm not particularly good at machining.

So, does anyone have any better ideas for a locking mechanism? Any hints on how to make a cam-lock?


Why?

The general idea is that there are two fixed near-vertical support posts, mounted from the ceiling and resting on the floor. The left support has a fence. Between these two posts are two horizontal pipes, basically making a large rectangle, big enough to hold a full sheet of plywood. Along the pipes runs an adjustable cutting support, mentioned above, that I can lock where needed. I'll also have two other vertical temporary supports that I can hang off the pipes where needed to support the panel I'm cutting. All of these supports will have a lower block where the panel I'm cutting can rest on, high enough up that my circular saw can get below the panel to start the cut, bottom to top.

In operation, I'll adjust the cutting support, sliding it along the pipes, to where I want the cut, lock it in place, hang a couple of supports where necessary, put the panel on the supports - on the lower blocks and up against the left fence, and slip the cutting guide over the panel with the pins going through the cutting support. Then, I lock the saw guild down, with the above-mentioned and yet undesigned cam-locks, effectively clamping everything solid. I can then make my cut with a circular saw running along the guide. Then, I release the guide clamps, pull out the cut piece, slide the panel to the left and up against the fence, clamp the guide back down, and make another cut. Repeat as necessary; each cut panel will be exactly the same size.

Why am I making this panel saw? Because I have a small shop... okay, I have a normal garage-sized shop with way too much junk in it. I can't fit a large tablesaw and my benchsaw fence can only get me up to 10" wide panels. After that, I have to start clamping guides and having at it with my circular saw. That's fine, except that getting the guide in exactly the right place, cut after cut, is, well, beyond my patience-threshold. Thus, my identically-sized panels aren't and my cases don't come together the way I want. Yes, I do woodworking, and metalworking, and automotive, and metal casting, and... well, that's why my shop is so crowded and why I'm trying to make a knock-down panel saw.

Any help appreciated,

David...

and no, I'm not looking to un-crowd my shop by giving my tools away :p

Quetico Bob
05-22-2008, 11:22 AM
Use the guide and clamp method myself and it can be tedious. Try a web search on push pull toggle clamps and vertical panel saws. Might give you some ideas on the parts you want to machine.
Cheers, Bob

TGTool
05-22-2008, 06:15 PM
I'm sorry, but I don't have a good picture of your problem from your verbal description so can't make any particular recommendations. Several places such as Garrett Wade and Rockler have woodworking fixture components. It seems like I saw cams that you could incorporate into special fixtures in one of them.

torker
05-22-2008, 07:09 PM
You mean something like this?
Put a rubber end on it and it'd work on slight different thicknesses..
http://img.photobucket.com/albums/v210/torker/DSC00001-56.jpg
Russ

Paul Alciatore
05-23-2008, 01:19 AM
I'm not sure I completely understand your design, but this company and others make a line of clamps that act in much the way you describe. Several of them could be ganged with connecting rods or cables.

http://www.destaco.com/default.asp?loc=USA&lang=ENG

or go to Reid for purchase:

http://www.reidsupply.com/results.aspx?N=1003805&On=1003805

I have used several of their clamps for wood working fixtures. The prices are reasonable and you can get a variety of accessories or even make your own.

All the usual disclaimers. I am only a satisfied user.

fixerdave
05-23-2008, 01:38 AM
I'm sorry, but I don't have a good picture of your problem from your verbal description so can't make any particular recommendations. ...

Okay, here's a picture - not a good one, but a picture. It's just a rough sketch of what I've got so far: (oh, and this is my very first attempt at images in this forum, so...)

http://fixerdave.googlepages.com/Panel_Saw_02.jpg


If that doesn't work, then I've created a page HERE (http://fixerdave.googlepages.com/project_panel_saw) that also includes a sketch of a cam-lock I'm thinking over. I think this version will work, and it's something I can make. However, I'm open to suggestions.

Basically, I need a mechanism that locks on the pull, rather than push.

Thanks for the replies so far,

David...

torker
05-23-2008, 08:03 AM
David.. kinda hard to tell from the drawing but do you want the pins to go through a hole and be held in place by a camlock?
If you look at my drill press hold down you can see how I used a cam to raise/lower the hold down. Same thing could easily be applied to a pin locking device.
Drilling the hole off center is how this was made. The more off center the hole, the greater the "cam action".
Russ

fixerdave
05-23-2008, 01:22 PM
David.. kinda hard to tell from the drawing but do you want the pins to go through a hole and be held in place by a camlock?
If you look at my drill press hold down you can see how I used a cam to raise/lower the hold down. Same thing could easily be applied to a pin locking device.
Drilling the hole off center is how this was made. The more off center the hole, the greater the "cam action".
Russ

Yes, to all 3 points.

1) The pins go through holes in the locking support. I want to clamp them from the back of this support. Sorry about the poor sketches - I'm still just thinking about this stuff. I'll attempt to CAD it up after the design settles down.

2) In looking at your photo, and thinking about it, I have realised that all I need to do is reverse the logic on a hold-down clamp. I actually have a commercial version of what you've made, though substantially less... substantial.

3) I now realise that I don't need to make some complicated shape to get a cam action, just a circle drilled with an offset centre. Which, given my machining ability, should be no problem at all :(


Your hold-down clamp uses a bolt to lock it to the shaft; the commercial one I have uses a clutch pack (like a bar clamp uses). I'm thinking both will be too cumbersome for repeated one-hand use. So, I came up with my own design (http://fixerdave.googlepages.com/project_panel_saw).

http://fixerdave.googlepages.com/Panel_Saw_01.jpg

Basically, to operate, I'd just have to slide the latch plate up such that it locks into a groove on the guide pin (instead of a bolt or clutch pack) and then rotate the cam to pull it tight and lock it in place. The operation should just be a flick of the wrist. The adjustment wheel has to compensate for about 3/4" in panel thickness variation. I suppose I could even make multiple grooves in the pins, reducing the need for adjustment.

Anyway,

Thanks for the pointers; sometimes I need a little kick to get past a design hump.

David...

fixerdave
05-23-2008, 01:55 PM
I'm not sure I completely understand your design, but this company and others make a line of clamps that act in much the way you describe. Several of them could be ganged with connecting rods or cables.

http://www.destaco.com/default.asp?loc=USA&lang=ENG ...

Hi,

Thanks for the link to the website. Even if I never buy anything they sell, they have great drawings of their mechanisms - great for ideas. I should be able to learn a lot from there.

David...