2 quick questions (blade tension / torsion box)

[Jim Hinze]

Hi all,

Hope you can help me out with a couple of questions...

1. Bandsaw blade tension: All bandsaw blades have drift, some more, some less. However, if you over tension a blade (particulary a timberwolf) would it make the drift more pronounced, less pronounced, or no difference?

2. Torsion box: Is there any hard/fast rules to the hight of the inner ribs of a torsion box? I want to build one for my tablesaw extension mounting a router... with a nifty cabinet (I want it heavier and flatter). Plan is to take 2 sheets of 3/4" mdf and make the ribs out of 3/4" mdf, but make it 1" high, so the overall thickness of the torsion box is 2.5" Will it be rigid enough?

Thanks in advance...

[Jeff Sudmeier]

Jim,

I haven't built a torsion box, so I am not sure on the min dimensions. However, I can say that most of them that I have seen built have been at least 2 inches thick and most times more like 2 1/2 inches thick.

Good luck!

Jeff

[Rick Lizek]

I made a similar one for my saw and used 1/4" luan skins. If you tap on it it sounds and feels like solid wood. Thicker ribs is what makes a torsion box work. 3/4 top and bottom is not necessary or wanted in this application. I had the torsion box stored in a damp unheated garage for 5 years and it's as flat as the day I made it.

[Bob Winkler]

I agree with Rick. The skins should be relatively thin. The primary advantage for torsion boxes is that they are very strong compared to their weight. 3/4" MDF skins would not be lightweight. 1/4" plywood would work fine. I made a whole closet full of torsion boxes as panels and shelves using 3/4" doug fir inner core and 1/4" cherry outer skins. Strong, light, and flat.

[Ken Garlock]

Jim, take a look at David Marks' program on the DIY channel website

Torsion Box assembly table (http://www.diynet.com/diy/shows_wwk/episode/0,2046,DIY_14350_26946,00.html)

[Jim Hinze]

Thanks folks...

I am actually out for both characteristics... a dead flat rigid table, and one that is quite heavy and won't easly rock or vibrate.

[Don Carkhuff]

Go to the dumpster of a door replacement store and "find" a solid core door. Cut it to size. I used them for workbenches and they perform great and have stayed flat for 15 years.

[Rick Lizek]

1/4" skins and 3/4 MDF will be more than enough. Leave a pocket sized in the middle for your router plate. I would recommend you check out the Woodhaven router bases. Very affordable and most flexible. Tilt base or top adjuster model is far less than any other brand.

[Dale Thompson]

Hi all,


1. Bandsaw blade tension: All bandsaw blades have drift, some more, some less. However, if you over tension a blade (particulary a timberwolf) would it make the drift more pronounced, less pronounced, or no difference?
Thanks in advance...

Jim,
Is this a multiple-choice question? :confused: If I had to bet my bottom-of-the-barrel reputation on the answer, I would guess that over-tensioning the blade would give you the "maximum" drift. One thing that I know is that you will not get rid of "drift" by over-tensioning the blade. :( If your drift is "outward" (ie. AWAY from the fence), which is usually the case, take a diamond hone and reduce or eliminate the "Rake" of the blade on the outside of the blade. :cool: :)

I don't like "drift". You may have to "putz" around a bit but it is well worth the time to get rid of it. ;) :)

Unfortunately, Scroll Saw blades have the same dang problem. On the positive side, they are relatively cheap. You are only out a few pennies if you mess up in terms of "adjusting" their rake. :o :cool: :)

Dale T.