Thread: Saw File Hardness Measurements

Originally Posted by BobL

I agree that hardness not likely to be the only factor in file acceptance but given the current data is not from the working area of the files I don't think any conclusions relevant to working files can be drawn from this data

The amount of effort that has gone into this experiment is indeed impressive and you guys are to be congratulated for this. To reduce your workload it would have been better to just target the business area of files i.e. don't worry about tang and heel measurements. The citric acid effect on hardness is immeasurable so I would have just left this out

I dislike creating more work for you and I'm sure you also know this, but testing just one file from each brand is also fraught with problems. It's like consumer testing " one of" a product from a manufacturer, every now and then, even quality manufacturers produce a lemon or indeed several.

The first thing I would have suggested is a pilot with just say 4-5 files of just two brands as this would have uncovered most of the experimental problems etc. If the hardness variability of files from the same manufacturer turns out to be greater than the difference between the manufacturers then that changes things significantly, even to the point where it may not be worth pursuing the rest of the experiment.

A number of times I have suggested that forum members about to embark on experiments should consider posting their design before they create a lot of work for themselves. Some of us have extensive experience in experimental design and reviewing of project proposals for national and international experiments.

Hi Bob,

Glad you joined in. I think we're also missing a needed analysis, i.e. scratch testing. Any ideas? As far as functional file testing I had another thought. I have a Foley saw filer too. It is actually a pretty consistent machine as far as filing a rip type profile goes and it doesn't get tired. What do you think of using it to work a set of files to death?

Cheers,
Rob

Originally Posted by rob streeper

I know they're bad but I'll do the testing just so we can have a complete dataset. Another point I wanted to raise: What are files 21 and 22? Did I miss something in the original report?

One of them turned out to be a Band Saw file, and the other one was taken because.....I can't remember but it was removed mid-testing.

Originally Posted by BobL

Crikey I would never have thought of doing it to new files.

There is a mob in the USA where you can buy your new files either stock standard or "Liquid Honed". They also run a used file sharpening service. On this page they talk about having your new purchases (from them) sharpened.

Practical Machinist

Originally Posted by rob streeper

Some sources state that for some alloys cryotreatment can double the scratch resistance. Is a similar effect possible with saw files? We have the technology...

Yes indeed - only way to find out is to have a go.

That was the same philosophy behind the acid sharpening. Too many said it works on old files - if it works on files that have had material removed from the teeth by use, then surely there must be a good chance that it will work on new teeth. But the answer was "no", in this case.

Originally Posted by rob streeper

Hi Bob,

Glad you joined in. I think we're also missing a needed analysis, i.e. scratch testing. Any ideas? As far as functional file testing I had another thought. I have a Foley saw filer too. It is actually a pretty consistent machine as far as filing a rip type profile goes and it doesn't get tired. What do you think of using it to work a set of files to death?

Cheers,
Rob

Do you mean "scratch testing" as is way of measuring hardness?

RE: Foley
Sounds like it would be useful provided it could be set up to somehow constantly feed material.
I don't think you'd have to work them to death - just look at rate of material removal and look for a "# of strokes to reach X g/stroke.

Originally Posted by BobL

Do you mean "scratch testing" as is way of measuring hardness?

RE: Foley
Sounds like it would be useful provided it could be set up to somehow constantly feed material.
I don't think you'd have to work them to death - just look at rate of material removal and look for a "# of strokes to reach X g/stroke.

For the scratch testing apparently the instrument used is a 'pin on disc tribometer' http://en.wikipedia.org/wiki/Tribometer.

For the filing test I was thinking of using a section of 0.035" thick 1095 steel about 20 inches long toothed at 12 or 13 tpi. Record the number of passes and the total depth of steel removed by each file up to the point that the file stops cutting.

Originally Posted by rob streeper

For the scratch testing apparently the instrument used is a 'pin on disc tribometer' http://en.wikipedia.org/wiki/Tribometer..

I'm not sure that a coefficient of friction measurement will be that useful.
I'm thinking about chainsaws and bandsaws. We can shape cutters that have very high coefficients of friction but they dig in so much that normal power sources cannot move them to cut effectively. If very high power is applied the cutters will just break

For the filing test I was thinking of using a section of 0.035" thick 1095 steel about 20 inches long toothed at 12 or 13 tpi. Record the number of passes and the total depth of steel removed by each file up to the point that the file stops cutting.

This sounds useful. Can the rate of feeding the material be made constant for multiple passes or does the operator have to adjust the pressure after every pass?
Or
Can the pressure being applied to the file be made constant?

Does the Foley lift the file when it moved it backwards?

Originally Posted by BobL

I'm not sure that a coefficient of friction measurement will be that useful.
I'm thinking about chainsaws and bandsaws. We can shape cutters that have very high coefficients of friction but they dig in so much that normal power sources cannot move them to cut effectively. If very high power is applied the cutters will just break




This sounds useful. Can the rate of feeding the material be made constant for multiple passes or does the operator have to adjust the pressure after every pass?
Or
Can the pressure being applied to the file be made constant?

Does the Foley lift the file when it moved it backwards?

The Foley filer has a pressure adjustment that is spring loaded. It does lift the file on the backstroke. The feed rate is constant on the cutting stroke. I'll think more about how to set it up and run some tests. If I can I'll post a video of the machine in operation. At this point I propose the following.

Test plate 0.035" 1095 steel 6 inches wide toothed at 12 ppi.

Run one preparatory filing to cut the teeth down past the zone of the plate that is work-hardened by the tooth punching operation.

Mark three teeth at the beginning, middle and end of the plate.

Measure using 0.0005" resolution caliper the depth of the plate from the bottom of the gullet to the back edge of the plate at each of the three test points.

Install a new test file in the Foley and set the machine to file every tooth.

At the end of the plate after all teeth have been filed one time stop, remove the test plate and measure the tooth depth at each of the three test points.

Continue filing and measuring until the change in tooth depth with filing becomes nil. Count the number of filings and the cumulative cut depth.

Repeat as needed.

Originally Posted by rob streeper

The Foley filer has a pressure adjustment that is spring loaded. It does lift the file on the backstroke. The feed rate is constant on the cutting stroke. I'll think more about how to set it up and run some tests. If I can I'll post a video of the machine in operation. At this point I propose the following.

Test plate 0.035" 1095 steel 6 inches wide toothed at 12 ppi.

Run one preparatory filing to cut the teeth down past the zone of the plate that is work-hardened by the tooth punching operation.

Mark three teeth at the beginning, middle and end of the plate.

Measure using 0.0005" resolution caliper the depth of the plate from the bottom of the gullet to the back edge of the plate at each of the three test points.

Install a new test file in the Foley and set the machine to file every tooth.

At the end of the plate after all teeth have been filed one time stop, remove the test plate and measure the tooth depth at each of the three test points.

Continue filing and measuring until the change in tooth depth with filing becomes nil. Count the number of filings and the cumulative cut depth.

Repeat as needed.

Sounds like a lot of work but if you are prepared to do it then it will be useful.
How many strokes does it do per tooth?

Originally Posted by BobL

Sounds like a lot of work but if you are prepared to do it then it will be useful.
How many strokes does it do per tooth?

Single stroke per tooth. It can also be set up to skip teeth for filing cross-cut saws.

I'm investing the time in doing this work because apparently nobody currently living has done these types of studies and published them.

There are a lot of people in saw making who talk about how things should be done based on a combination of their personal experience and received, but unchallenged, wisdom. Systematic studies are almost non-existent. I know that these studies are limited, unfortunately the resources needed to do comprehensive work are lacking. Nonetheless systematic studies, even limited studies, are a step in the right direction.

Originally Posted by rob streeper

Single stroke per tooth. It can also be set up to skip teeth for filing cross-cut saws..

Can you get it to repeat the sequence automatically or do you have to restart it manually.

On the milling bandsaw auto band sharpener this drive the band around and around ad nauseum

.

I'm investing the time in doing this work because apparently nobody currently living has done these types of studies and published them. There are a lot of people in saw making who talk about how things should be done based on a combination of their personal experience and received, but unchallenged, wisdom. Systematic studies are almost non-existent. I know that these studies are limited, unfortunately the resources needed to do comprehensive work are lacking. Nonetheless systematic studies, even limited studies, are a step in the right direction.

A common enough occurrence and good on you for giving it a crack!

The same thing happened in chain saw chain sharpening.
When I started to get serious about chainsaw milling I was surprised to find that no one had had determined the optimum depths for chain rakers
The consumer level raker setting jigs sold by chainsaw and chain companies were too shallow and did not take into account cutter wear and sharpening so the more the cutter was sharpened, the more wrong the raker jigs were. This typically lead to operators filing the cutters more often and making the situation worse until operators gave up and bought new chains.
Very few, even professional, chainsaw operators knew about this issue even though a range of raker depth setting jigs were available.
Even the range of raker depth setting jigs are still not the correct way to set the rakers accurately so I came up with a way of doing it with a digital angle finder which I put on Youtube (youtu.be/FSr9j2EDoqk) and on a US Chainsaw forum. This generated a lot of discussion but everyone that has adopted this now swears by it.

BTW Chainsaw sharpening is the main time I use files. A box of a dozen round files lasts me a long time and the flat files I use for rakers I just buy a cheapie around 1 - 2 years.

Originally Posted by BobL

Can you get it to repeat the sequence automatically or do you have to restart it manually.

The blade needs to be re-positioned in the filer after each pass.

Please post a link to your raker gauge post on the chainsaw forum you mention.

Originally Posted by rob streeper

The blade needs to be re-positioned in the filer after each pass.
Please post a link to your raker gauge post on the chainsaw forum you mention.

Here 'tis.
http://www.arboristsite.com/communit...rators.114624/

By all means tackle the whole thread but the first dozen or so posts are a discussing of a specific gauge setting device called and FOP (File O Plate) a gauge made by Carlton chains.
It's around post 25 where I go right back to basics and explain my understanding of how chains cut and in subsequent posts I explain what I do in more detail

Given the hardcore nature of the members on that site the feedback I got from this thread has been very positive e.g.

As said before, by other members...One of the best threads on the site. I've learned a bunch and will try this the next time I sharpen. Thanks Bob...

Because the members liked this thread so much the mods made it sticky and its the only sticky on this particular forum
Be warned it is super nerdy, not unlike some threads on these forums.
There's even a photo of my hand saw tooth indexer in there!
The arborisite forums were down a few years back and they lost most of their pictures.
This thread is so popular (26k views) I went back in and re-inserted my pics but most of the other poster images are gone.

I posted similar information on these forums here.
https://www.woodworkforums.com/showth...=107669&page=1
Only about 1/4 as many views as the .arboristsite but playing to a much smaller audience of course.

Thanks Bob. Surprising how frequently people fail or refuse to think.

Originally Posted by rob streeper

Thanks Bob. Surprising how frequently people fail or refuse to think.

Yeah.......I'm all for challenging conventional wisdom. Most of the time it's right and I learn a very great deal in the process of the challenge, but sometimes, just sometimes, it yields new info and a better way.

It's all about Granny's Frypan.