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Hello,

I'm looking at moving to the fiberglass marker (from big box home stores) for go-bar clamping. I like the idea of being able to just grab a few extra when it's needed and I think I can make it work so that I don't need a dedicated go-bar deck. This will save me some space.

This has been discussed before on the forum but I have some questions.

Setup:
1) Roughly 36"x36" cabinet on wheels. So I can roll it in and out of the center of the room.
2) Radius dish mounted to 24"x24" base. All my radius dishes are mounted this way.
3) Ceiling mounted plate with position holes drilled in a grid every 1/2" or so (so the pointed end of the rod "snaps" into place). This is not pictured. The pic is just using the air filter as an example.
4) Fiberglass rods from HD.

Ok, so it looks like I can fashion the ceiling plate so that my air filter is basically sitting on top of it. This is the center of the room and would give me full 360 degree access to the work.

Question:
Looking at the pics below, is the rod going to give the right amount of clamping pressure? I seem to recall a post stating that if the rod is sprung like pic 1 or 2, it would still give roughly the same clamping pressure. Is that correct?





Thanks!
Brad



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Picture 1 is better.

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I'd be worried about the slippery metal surface of the air filter. Plus when you have like 20 of those bars that's a lot of force. Is that air filter mounted very securely?

Once again, I've probably confused the situation.

The air filter is just a proxy for now to show where the permanent board would be mounted. I'm thinking I would mount a 3/4 plywood board to the ceiling as a "shelf" of sorts that the air filter would then sit on. So yes, it would be secure.

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Casey, question for you.... I'm trying to avoid making something adjustable for top / back bracing vs. gluing top and back plates to the rims. Picture 1 shows how sprung the rod is when clamping braces to a top or back. Picture 2 shows how sprung the rod is when clamping a top or back to the rims.

My understanding is that both of those would roughly give the same clamping pressure. Is that not the case?

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This is pretty much exactly what I use but it is not in the middle of the room. At first I planned to have several lengths of rod for different height requirements. In practice, I stopped cutting shorter ones and just use full length rods with more spring in them for taller glue ups. Once you get to a certain point of deflection, you don't really get much more pressure with more bend so it is really a matter of having a bunch of really big bends is inconvenient but workable. Some of my glue ups look pretty dicey but I have not ever had a problem. Shorter rods will provide more pressure but these rods are thick enough that long ones are not weak by any means.

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

Thanks, Bryan! This is what I had in mind as well. Trying to avoid have different lengths or an adjustable plate at the top. Makes it all easier to manage.

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Seems like many of you use the fiberglass rods... I know I curse the ones my daughter has in the field for her electric fence, because they always "decay" and if I touch them I get a handful of glass fiber... I'm assuming that's due to weathering/sunlight... but there's no issue inside a shop?

On a side note, the ceiling is the worst place for an air cleaner as far as efficiency goes. I have mine on the floor under a bench. Dust settles - much faster than you think!

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Interesting! The manual said to mount it to the ceiling as close to the center of the room as possible. I'm not sure where I would put it on the floor but that is worth some experimentation.

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Check out Euler's formula on the bending of a column, which basically says once the bending reaches a certain point more force will cause more bending but no change in the down force. Put a scale, bathroom style will work, the rods need to apply 8 to 10 lbs of force when bent into working position. You can then increase the bend as when a body is in the deck and measure the change of pressure with the scale.

Fred

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Fred Tellier
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I found a picture of my deck in use. This is a mandolin bridge plate being glued; it sat lower in the deck than normal so there is slightly less bend in the bars. The picture shows some short bars (orange) that probably could use some more flex to reach full force because it is sitting lower than usual. The longer bars (yellow) are quite bowed. This is mildly inconvenient for me but not as much as having multiple bars.



As stated, the extra bow does not provide extra force. The short bars in the picture are not providing full force because they are not bending far enough. The shorter bars provide more force (when bent enough) than the longer bars of same diameter can. . .

My bars have been used a fair amount and only occasionally will I get a fiberglass splinter and usually when I do, it is from a bar that has been cut down. The driveway markers I use are coated enough that I think they will hold up well indoors. Since they are readily available, I can easily replace any that to end up giving me splinters.

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

I use the fiberglass rods sold for kites http://intothewind.com/Item--i-422 I cut the 48" rods in half and use the plastic caps they sell for them on the ends. I have not had any fiberglass delaminate in the 8 or so years I've been using them. IIRC they provide between 7 and 8 lbs of down force. As far as your photo 1 and 2 goes both will have the same down force, photo 2 will have a greater additional sideways force that makes it more likely to injure or cause damage if it comes loose. Put the rod on a scale and flex it, you will see what we're talking about.

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Steve Smith
"Music is what feelings sound like"

I know its a little off topic but I'd double down on what Andy said -- air cleaners at floor level tend to be more efficient -- gravity, downdraft.

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Ken Cierp

http://www.kennethmichaelguitars.com/

The sideways force will be determined by how well you locate the ends plumb to each other. If the top end is perfectly plumb to the bottom it will all be down-force. In practice, you never get them perfect. The bigger the arc in the bar the more exaggerated the effect. But even with bars that are way too long, it is not that hard to get them lined up close enough. I usually get one positioned right where I want it and then visualize where the others go based on that point on the top deck. It is hard to explain, if I put one bar at the center of the X then all the other ends will go in making an x and all the other bracing on the top. This will be even easier with the pegboard you plan to use since you will have a built in grid.

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

I've read lots of pro and con arguments on woodworkers forums about where to place air cleaners. Two issues with placement on the floor is one, the obvious one, that most shops have too much stuff in them like work benches, power tools, cabinets etc so you have bad air flow. If you can't get proper air flow then the air cleaner will never work properly. Second is that the dust down on the floor isn't gonna get into your lungs anyway because it's down on the floor. So that's why many recommendations are to place them at around breathing height or hanging just below the ceiling and close to a long wall preferable angled so that the clean exhaust air will flow and bounce off the walls creating a circular pattern right back to the intake.

Sorry about the thread drift

We are not talking about the same thing Bryan. If the top and bottom are located perfectly over each other there will be no sideways vector at those points but the more you flex the bar the more potential energy there will be in the X direction (sideways). If the bar was suddenly released then a bar that is flexed more will fly farther (easy to test) and be more likely to damage you or other stuff like guitar tops. As you continue to flex the go bar there will be a point where you will see no increase in vertical force, the extra energy is going into the sideways potential energy. Not sure I am explaining this very well. Come on over to the shop and I can show you what I mean - then I'll buy you a beer

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Steve Smith
"Music is what feelings sound like"

Nope, I got it now. I thought you were talking about the tendency for poorly aligned pars to scoot your work across itself.

Yes, there is much more energy stored in a bar that is longer than needed. Extra care should be taken to keep them from flying around, therein lies the inconvenience of having your bars too long. You trade off one inconvenience for another. I've had the long bars slip off a few times and they always have ended up just pushing down on the nearest adjacent surface (the top itself or the radius dish) without going anywhere or knocking others off. Keeping then lined up vertically helps reduce the tendency for them to go flying laterally DAMHIKT.

The most dangerous time IMHO is when you are unclamping them. Putting them in, you are naturally more careful and aligning them well. When you go to take them out, they have a tendency to release their energy sooner than you expect. It is the top end of the bar that wants to go shooting out because you are not holing it firmly enough. All the other bars are still there and it can get dicey. Just remember to take them off carefully and systematically.

Just because I already know what you mean doesn't mean that I won't take that beer. . .

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

Ok, here is V1. We will see how it goes this weekend.






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Brad--

Only one question:

How stationary is the mobile cart when you are using it as the bottom of the go bar deck? I could see problems if the wheels don't lock well. I would want to use a mobile tool base that "drops" the cart onto the floor when you want it to stay put, and picks it up onto the wheels when you want to move it. But if the wheels have sturdy locks, maybe that is good enough. This is the only thing that caused me concern; it othwise looks like a good way to save space.

Great looking go-bar deck AND shop Brad!

Don brings up a good point. Even if the wheels lock but are on swivel casters a nudge could twist the cart enough that all the bars loose their footing and could set off a room full of mousetraps effect.

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

Good point, Don. The wheels are locking casters from woodcraft. They do lock pretty well and the concrete floor is relatively level in this area. All four wheels have pretty good purchase on the floor and once locked it doesn't want to move around. That being said, I do have an extra mobile base that I used with a previous bandsaw. Might be the way to go. I'll play with things more this weekend.


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I set mine up on a fold up stand so I can put it under my table top when not using it. The peg board top works great but I've started wearing safety glasses while putting the rods on and off. Had a few slip and shoot across the room. Even with squares edges I find the rubber tips marginal. I'm making a handful of cauls with ice cream stick "skirts" to stop the tendency to roll.K



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Brad Hall
Mystic Dawg Guitars

The only thing that I would like to add is to make sure you wear safety glasses when using any go-bar deck. If one slips, it can set off a domino effect of fibreglass rods flying all over.

Alex

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