Band saw tension guage

Mark_f

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I have been doing some research and a little experimenting with my Chinese band saw. I have made many modifications from all the posts on the internet and my saw works pretty good. It is an OLD, old, old Champion Machinery saw which is still the same castings as the new saws. I got mine a little over 10 years ago from an old barn. It was so dirty no one actually new what the pile of dirt was ( but I did). The owner gave it to me to get rid of it. Cleaning, more cleaning an did I mention cleaning fixed it up like new. It cuts square and straight but slow. I use good blades. With some education from the guy that makes my blades and a good bit of help from the Starrett company I have much improved the performance. I have been taught to look at the chips the blade spits out and determine if the speed needs upped or reduced and if the down force needs increased or reduced. All this turns out is really simple stuff, BUT I DIDN'T KNOW IT and now my saw works much better than it had. Now to the project. I use bi metal blades and my blade guy (and Starrett) said they need to be TIGHT! Blades up to 1 1/4 inch wide need to be 25000 to 30000 psi tension. They both told me to be in the low end to middle of that range to get optimum performance from my blades and saw. So I need to build a tension gauge as I am not laying out $300 for one. This project is costing me almost nothing as I had this small piece of aluminum plate lying around and I bought the indicator on "the bay" for $5 brand new ( what a find, this is an expensive indicator).

WP_20141130_18_06_52_Pro.jpg This is a simple project. It has three pieces, but a good bit of machining. The body and the lever arm which are made from aluminum and then the indicator. This photo shows the pieces all laid out and ready to machine. I am using a 2 1/4 inch diameter Federal indicator that reads each division as .0001". I got the print from the internet, but it was made for a mitutoyo indicator so I had to re calculate several dimensions to fit my indicator. I will post photos as I machine the parts.


Mark Frazier

WP_20141130_18_06_52_Pro.jpg
 
Interesting and useful project. I'll be interested in seeing it done and a picture in service.

Please, also share what you have learned about chips vs blade speed and down force(?).
 
Interesting and useful project. I'll be interested in seeing it done and a picture in service.

Please, also share what you have learned about chips vs blade speed and down force(?).

I am amazed at how simple the answers I needed were. There ain't no big lengthy scientific bunch of info here. My cutting was slow and the first thing the blade rep asked was " what do your chips look like". I picked up some chips and they were basically powder. He said" if your chips look like powder, your cutting feed rate needs increased. The chips should not be powder, they should be a short loose curled chip. If the chip is tightly curled the feed rate is too fast. ( we are talking the cutting down force).

Next he wanted to know the color of the chips. if they have any blue color The blade speed is too fast. they could have a LIGHT straw color. A silver chip is maybe a little too slow blade speed but not bad. This is where I am now running because I don't want to push the saw or blade.

The next issue was the blade tension. he said if the tension was not high enough the saw won't cut straight at the proper speed and feed and if the tension is too high the blade life will be shortened and it will break. Even though I cranked the crap out of my tension knob ( in my opinion) the tension was a little too low.

I switched to a 6 /8 combo tooth, 1/2" wide, .025" thick bi metal blade. this is to help the carrying of chips and keeping the cut clean which improves the finish of the cut. this tooth blade will suffice for most stock from fairly small ( like 1/2" through 2"). Smaller stock ideally would use a finer tooth blade but to avoid changing blades, I will reduce the feed a little to compensate and not have to change the blade ( don't want it to grab or dig in ). Large stock ideally should have a lower tooth count per inch but the blade I am now using will suffice for all work I want to do. (changing the blade to be that precise is only beneficial in a production setting, not worth the trouble or cost for the hobbyist. He said the ideal cutting would be a minimum of three, preferably four teeth in the cut and a maximum of ten to twenty teeth in the cut at all times, but again this would be a production situation. A lot of leeway is ok and the hobbyist can get away without being too fussy. While not entirely necessary , I was told I could extend blade life just by lifting on the saw when starting a cut till minimum tooth count was in the cut and doing the same at the end of the cut. I do this sometimes. The saw slamming into the material at the start can break teeth.

He gave me a lot of printed charts and information which you can download for free from the Starrett website and all this info is in there.

After implementing these changes, my saw is cutting twice as fast as it was and the finish of the cut is very flat and smooth ( it almost looks machined) I checked my cut with a precision square and I doubt I could machine it any closer. This is going to save me hours of work because I no longer have to set up and mill a saw cut unless it has to be a perfect finish or tight tolerance on size.

Some may think this is a lot of hog wash, but I am very happy with the improved results just with a couple easy changes and the only cost is the proper blade. I will post pics of my tension gauge and while it is in use.

I won't post the print here because I don't know if it would be legal to post as although it is not "copy righted", It does say whom it was drawn by and that it cannot be published or reproduced for other than personal use. I did have to make several dimensional changes for my indicator. I found it by Googling saw blade tension gauge images and saw this one, went to the site. It can be downloaded by anyone .

Again, all this has made a tremendous difference in my saw. I don't know how anyone else will fair from this as it depends on how well you were doing in the first place, but I AM HAPPY! :happyhappy:

Mark Frazier
 
Great project Mark. Is this of your designing. I have wanted one of these for a while but whenever one showed up the price was out of reach. I will be watching your progress.

"Billy G"
 
Great project Mark. Is this of your designing. I have wanted one of these for a while but whenever one showed up the price was out of reach. I will be watching your progress.

"Billy G"

Actually no, it is not my design, I had to modify it to work with my gauge,but that is easy to do and it is easy to make. It was designed by Martin Kennedy and was published in The Home Metal Shop Club newsletter a few years ago, but in his article, he said he never built it because his problems were caused by other things and solved them before he had a chance to build the gauge.

This one is very close to the Starrett gauge.

Mark Frazier
 
Hello Mark;

Found their site Mark. You wouldn't happen to know what year? There are a lot of news letters there.

"Billy G"


Found it, Volume 16 August 2011, Pages 7-9 . Looks like fun.
 
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Hello Mark;

Found their site Mark. You wouldn't happen to know what year? There are a lot of news letters there.

"Billy G"


Found it, Volume 16 August 2011, Pages 7-9 . Looks like fun.


Glad you found it.

Mark
 
Actually no, it is not my design, I had to modify it to work with my gauge,but that is easy to do and it is easy to make. It was designed by Martin Kennedy and was published in The Home Metal Shop Club newsletter a few years ago, but in his article, he said he never built it because his problems were caused by other things and solved them before he had a chance to build the gauge.

This one is very close to the Starrett gauge.

Mark Frazier

Hello Mark;

Found their site Mark. You wouldn't happen to know what year? There are a lot of news letters there.

"Billy G"


Found it, Volume 16 August 2011, Pages 7-9 . Looks like fun.

Glad you found it.

Mark

By chance, does anyone have a link to the site... :)

THX

John
 
There is a conversion chart to convert the tenths reading on the indicator to psi. I will post it tonite sometime.

Mark Frazier
 
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