Second Bandsaw Questions/Advice
Hi Everyone,
In what I'm sure has been discussed before, I'm interested in the current point of view of the SMC membership. I have a Felder FB510 20" inch bandsaw with ceramic guides that has usually been fitted with a 1" Woodmaster CT for ripping and resawing. I generally tension the blade to near maximum and get reasonable performance. I like the large table and ability to add Aigner extension tables easily. I recently sold my Laguna LTSEC which was a Meber-built Italian 16" saw because I thought I needed the extra room in my shop. I'm getting tired of changing the blades on the Felder and am thinking of going back to a 2-bandsaw shop. My question is whether to add a larger dedicated resaw (like a 20" SMC-Minimax) that will better tension the 1" Woodmaster CT (or Trimaster, etc) and use the Felder for smaller blades or continue to use the Felder for resaw and purchase a smaller steel-spined saw that will easily take blades down to 1/8". I want to avoid a much smaller table than the Felder and think that for smaller blades crowned wheels and a higher table to floor height would be nice, perhaps a Grizzly G0514X2: large table, 37" to the floor and 3 hp motor with crowned wheels.
Any thoughts/advice/suggestions/experience?
Thanks.
Ed
1 Attachment(s)
measuring bandsaw blade tension
Ed,
Perhaps you can measure the actual tension which might help decide what to do next. The gauges provided on bandsaws are notoriously inaccurate so you probably need to measure it with a bandsaw blade tension gauge.
I use a Starrett gauge and I was surprised at how much below the recommended tension my blades were. Instead of buying a tension gauge, you can use a digital caliper to measure the tension. John TenEyck once posted instructions which I've copied below, or read the whole thread:http://www.sawmillcreek.org/showthre...33#post2640833
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HOW TO MAKE AN ACCURATE TENSION GAUGE for free or cheap
Needed: digital caliper, small clamps, math
By John TenEyck
(Measuring tension with digital calipers)
...the blade guides are removed or at least backed away from the blade. Clamp the vernier with about a 5" gage length so that each jaw is on the flat of the blade, between two teeth. On really narrow blades it's best to face the vernier towards the back of the saw in order to avoid the teeth altogether.
The basic calculation is Young's Modulus = Stress/Strain, where:
1) The Young's Modulus of steel is about 30 x 10^6 psi.
2) Stress, the value you are after - the tension in the blade in psi.
3) Strain = Deflection / gage length. The vernier measures deflection, and the gage length is the starting distance between the jaws under zero load.
So, you rewrite the equation as Stress = Young's Modulus x Strain = 30 X 10^6 x deflection/gage length
The gage length I started with was 4.768", so when I measured a deflection of 0.003" that was equal to a blade tension of 30 X 10^ x 0.003/4.768 = 18,876 psi.
My little Delta was more than maxed out with the 1/2" blade I was using. The Iturra spring was nearly fully compressed, the frame was distorted by nearly 0.010" and that pulled the upper guide completely out of alignment. The data showed that I can't really run more than about 12K psi on a 1/2" blade. But with a 1/4" blade I can run at nearly 25K psi w/o over stressing the saw. The 1/2" blade will still cut OK at 12K psi, but I have to run more slowly than I would if I could apply higher tension to avoid blade deflection.
John TenEyck's photo:
Attachment 399367
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Quote:
Originally Posted by
Ed Weiser
Thanks to all for some insight. Additional info: Here is a photo of 14" wide walnut that I just cut 1/4" thick. The blade is a 1.3T Woodmaster CT. The saw is maxed out on tension (extent to which wheel will turn before bottoming out) minus one half turn. The cut was easy and uniform, hand fed. I still get the feeling that the blade could have more tension though. Could the blade be a little long? Felder specs 170" and that's what bandsawbladesdirect was asked to provide. When I detension the blades completely, there is about 1.5" of gap of blade above the top wheel of the saw. Any thoughts?
I will spend for another saw what it takes to get the right combination. I just don't want to duplicate what I already have.