Thanks: 0
Likes: 0
Needs Pictures: 0
Picture(s) thanks: 0
Results 1 to 11 of 11
Thread: Tension measurement?
-
13th April 2008, 07:29 PM #1SENIOR MEMBER
- Join Date
- Feb 2007
- Location
- Adelaide
- Posts
- 595
Tension measurement?
I know that all you experienced people have confidence that you can tension just until you strike that right musical note from the blade. I am much more apprehensive and tone deaf. Some professional tension measuring devices are expensive and appear to measure the increase in length between a short portion of the blade when it is put in tension, using a dial indicator. A recent FWW article described a home-made gadget using feeler gauges that is supposed to work on a stretching of the blade over about 125mm (5 inches) by about 0.07mm (.0025 inches) when the tension is right. But I am not confident that I can use feeler gauges with that degree of sensitivity.
So, I am trying to be inventive. If 125mm of blade is to stretch 0.07mm with correct tension, then the full length of a blade, say 2500mm should stretch 20 times that, or 1.4mm. Now assuming that all blade elasticities are the same, and assuming (a big one I know) that the stretch can only occur by increasing the distance between the two spindles, the top spindle should go rise 1.4/2 = 0.7mm between the zero and appropriate tension. With a straightedge between the wheels, this is almost enough to eyeball without feeler gauges. But, if the blade bedded deeper into the rubber tyres under tension, the centres would need to move even further. Has anyone thought about this before and got ideas to add
Maybe I should just get a tuning fork
-
13th April 2008 07:29 PM # ADSGoogle Adsense Advertisement
- Join Date
- Always
- Location
- Advertising world
- Posts
- Many
-
13th April 2008, 10:54 PM #2
Fencepost2
I've no doubt I am about to incur the wrath of the ????'s with my response, but what the heck!
Your question reminds me of an image I have of all the workshops in the world that have and must use a precise system in which the occupant's tools and machines are kept and must be in place when ever ! Whenever they present an image of their workshops where are the signs of accumulated dust or wood shavings, everything is in it's place! I can assure you this is the very reason why I've never posted any images of my most favourite place in the world - my workshop!
My advice is to stick to the tried and proven system ~ get to know your equipment ~ use it, know how it works, know how to get the best from it. Be prepared to take the time to learn. Don't rely upon anyone else, by trusting your accumulated knowledge I guarantee you'll get more value and satisfaction than any off the shelf devicesTony Ward
Now a power carver and living the dream.
-
14th April 2008, 11:22 AM #3
ping!
I rest my case.p.t.c
-
14th April 2008, 11:41 AM #4SENIOR MEMBER
- Join Date
- Feb 2007
- Location
- Adelaide
- Posts
- 595
Tony and PTC, thank you for your pings. A lot of wisdom there Tony. I suppose a lot of my enjoyment of woodworking is exactly what you say, getting to know how things work and what makes things happen. I do most of my woodworking in bed between the hours of about 5am when I wake up, and about 7am which is a decent time for me to get up. I like to figure things out in my head and then maybe test them in the workshop later on. My proportion of shavings, dust, and firewood against finished product is about 10:1. But it is fun and there is so much to learn and enjoy. My next batch of puzzling will be about why I can only bandsaw circles about twice the radius the charts say I should be able to do
-
14th April 2008, 01:00 PM #5
On that one, don't forget to round the back of the blade - gives you a much better radius capability and is not detrimental to the blade. Of course, Tony is the resident expert on bandsawing radiuses, so I'm sure he will have a much more considered answer!
"Clear, Ease Springs"
www.Stu's Shed.com
-
14th April 2008, 04:42 PM #6SENIOR MEMBER
- Join Date
- Feb 2007
- Location
- Adelaide
- Posts
- 595
Thanks Stuart, how obvious and yet I had not thought of it. Makes good sense, round it with a stone I imagine?
-
14th April 2008, 04:48 PM #7
-
14th April 2008, 06:48 PM #8GOLD MEMBER
- Join Date
- Oct 2002
- Location
- NSW
- Posts
- 1,610
Probably a good idea to clean out any accumulated wood dust from the bandsaw before rounding the blade - there was a fair bit of sparking when I did mine, and no sense risking fire.
Hope I'm not patronizing if I clarify how I rounded the back of my blade:
1) work out some way of getting the stone to touch the blade, whilst keeping fingers well away! A common suggestion is to glue the stone to a longer piece of wood.
2) rest the stone on the bandsaw table, and just *lightly* touch it to the back of the blade with the saw running. Swing it round the back of the blade to smooth off the 90 degree edges.
Cheers,
Andrew
-
14th April 2008, 10:06 PM #9GOLD MEMBER
- Join Date
- Jun 2005
- Location
- Helensburgh
- Posts
- 7,696
I just tension them, it doesn't seem such a big deal to me. But I can understand wanting to know more so read this thread...
http://www.sawmillcreek.org/showthre...=Mark+Duginske
Mark is the guru in bandsaw or at least one of them with several well read books to his credit. Read the whole thread and most if not all tension devices are tested and generally written off as not worth having.CHRIS
-
14th April 2008, 10:37 PM #10
-
15th April 2008, 02:16 PM #11SENIOR MEMBER
- Join Date
- Feb 2007
- Location
- Adelaide
- Posts
- 595
Thanks again everyone, and to Mini for referring me to a long thread which debunked various kinds of tensioning devices.
What I have learned is that I should be more "empirical" that is, use the scale on the machine, try something out to see if it works, if it does, stick to it, if it does'nt make and adjustment.
Similar Threads
-
rpm measurement?
By Slow6 in forum WOODTURNING - GENERALReplies: 24Last Post: 20th November 2006, 12:46 AM -
Measurement converter
By keith53 in forum WOODWORK - GENERALReplies: 35Last Post: 22nd August 2006, 03:54 AM -
What is the exact measurement?
By Marchalis in forum WOODWORK PICSReplies: 7Last Post: 3rd November 2005, 09:15 PM -
Router table measurement
By dazzler in forum TRITON / GMCReplies: 9Last Post: 8th June 2005, 10:22 AM