Is this scrap?

This topic has 21 replies, 12 voices, and was last updated 6 February 2012 at 23:50 by chris stephens.

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4 February 2012 at 17:43 #5921
Wolfie
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@wolfie
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4 February 2012 at 17:43 #83846
Wolfie
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@wolfie
I reckon I’ve killed this slitting saw is there any point in trying to sharpen it or do I chuck it.

Not quite sure how I did it, maybe running too fast?
4 February 2012 at 18:08 #83849
jason udall
Participant
@jasonudall57142
you never know.
They can be sharpened but not realy at home unless you need a new hobby…3*3.142*tpi teeth and hss..
Cost of regrind prob. exceeds cost of new saw..
But steel might be handy as “washer”
4 February 2012 at 18:11 #83851
Richard Parsons
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@richardparsons61721
No get a little “3 square” emery stone or a diamond file and one day start to sharpen it. It will do a ‘turn’ when you need it.

Good practice

Rdgs

Dick
4 February 2012 at 18:13 #83852
jason udall
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@jasonudall57142
like I say … new hobby
4 February 2012 at 18:23 #83854
JasonB
Moderator
@jasonb
You do need to run them quite slow, probably as slow as your little mill will go and use suitable cutting fluid for the material being cut.

One other thing if you were using that 1.0mm saw to try and do your clevis you will find that as the slot can’t be done with one cut that the saw will tend to deflect into the previous saw Kerf. You really want a specific blade width for each likely slot eg, 1/16, 3/32 & 1/8 and the same if you work in metric 1, 2 & 3mm

J
4 February 2012 at 18:50 #83859
John Stevenson 1
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@johnstevenson1
Ideal speed for slitting saws is as slow as you can go, then halve it

Don’t care what any tables say I’d run a 3″ saw at 80 revs max in steel with loads of cutting oil.

And NEVER use the key to secure it, first time it hangs up instead of slipping the key will split and shatter the saw and you will end up wearing it.

John S.
4 February 2012 at 20:45 #83871
Sub Mandrel
Participant
@submandrel
The ‘building the quorn’ book explains how to sharpen slitting saws.

It’s not that hard really as gthere is no relief, you just need a wheel with a good corner to get into the tooth space and grind the front of each tooth back to its original profile.

You wpould have to make some sort of holder for the blade, but indexing is easy – just use a bit of springy metal against a tooth and after you sharpen each tooth click around to the next.

Neil
4 February 2012 at 20:59 #83874
,
Participant
@nousername29627
Life is too short to sharpen slitting saws!
5 February 2012 at 14:08 #83938
Russell Eberhardt
Participant
@russelleberhardt48058
Harold Hall published a design for a jig (or is it a fixture?) for sharpening slitting saws on his grinding rest. I have built one and it only takes a few minutes to sharpen the saw while it takes several days to get a new one sent mail order!

Most small mills run the spindle much too fast on their lowest speed for using a slitting saw. That was my initial reason for fitting a variable speed drive.

Russell.
5 February 2012 at 14:29 #83941
Terryd
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@terryd72465
Posted by russell eberhardt on 05/02/2012 14:08:11:

Harold Hall published a design for a jig (or is it a fixture?) for sharpening slitting saws on his grinding rest. I have built one and it only takes a few minutes to sharpen the saw while it takes several days to get a new one sent mail order!

Most small mills run the spindle much too fast on their lowest speed for using a slitting saw. That was my initial reason for fitting a variable speed drive.

Russell.

Hi Russell,

According to Wikipedia it is a jig. Apparently the difference is that a fixture secures items for working on while a jig controls the tool as well, so Harold Halls device holds the workpiece and effectively guides the tool (although you move the work against it but you could arrange the grinder to move to the jig) so it must be a jig. We used to build welding fixtures for manual welding (I wasn’t involved) and of course the welder controls the tool, while the jigs we made for the motor industry held panels for welding with fixed spot welders, effectively the tools were controlled by the jig.

Terry
5 February 2012 at 15:02 #83945
Terryd
Participant
@terryd72465
Posted by Wolfie on 04/02/2012 17:43:31:

I reckon I’ve killed this slitting saw is there any point in trying to sharpen it or do I chuck it.

Not quite sure how I did it, maybe running too fast?

Hi Wolfie,

You could cut it into strips with a thin cutting disc and have a supply of HSS thin parting tools .

I agree with others that it is speed that kills with these. Also as John S said never use the key slot to secure it. Don’t bin it, keep it ’til you build HH’s Grinding rest and the saw sharpening jig.

Best regards

Terry

Edited By Terryd on 05/02/2012 15:05:49
5 February 2012 at 15:04 #83946
John Stevenson 1
Participant
@johnstevenson1
The correct way to grind slitting saws is to grind every alternate tooth in the same direction then either reverse the wheel or swap the saw over and do the other teeth in the other direction.

The idea is the burrs thrown up by grinding give some clearance. Same for cutters with clearance teeth, always throw the burrs off the edge, not onto the cutter.

John S.
5 February 2012 at 16:10 #83949
Terryd
Participant
@terryd72465
Hi John,

Thanks for that tip. I’ll remember it when I have one to do. There’s always something to learn.

Best regards

terry

Edited By Terryd on 05/02/2012 16:11:31
5 February 2012 at 16:35 #83951
Anonymous
Bin it! The saw is pretty fine pitch; that’s fine (!) for slotting screw heads, but not much use for anything else. For any decent depth of cut you’ll need a much coarser tooth pitch so that the gullet (space between teeth) is bigger so the swarf won’t jam the saw.

Regards,

Andrew
5 February 2012 at 19:26 #83967
chris stephens
Participant
@chrisstephens63393
“Bin it” BIN IT are you mad, they cost money you know.

It can easily be sharpened , admittedly if you have the kit, and converted to a deeper gullet coarser blade at the same time. The only time you bin a blade is if you completely c*cked up and shattered it. Even then, as has been suggested, you can use the steel for other things.

All you “bin it” people must be youngsters and be infected with the modern virus called “throwawayage”.

chriStephens
6 February 2012 at 12:04 #84025
,
Participant
@nousername29627
No – I am not a youngster but I value my time and the older you get the more you realize how limited and valuable it is. I certainly do NOT waste it by sharpening slitting saws, hacksaw blades, centre drills, end mills (all explained in the Quorn book) or even drills under 1/8. Settig up the grinder, jig, fixture or whatever you use takes far too long – just try setting up the quorn and sharpening the ends of the teeth and the helix and see how long it takes”and unless you have an air spindle the results are suspect at best.

STOP WASTING TIME!
6 February 2012 at 12:38 #84030
chris stephens
Participant
@chrisstephens63393
Talk about wasting time, make yourself a stationary engine and have it sit on

the mantle shelf doing nothing except collect dust, but make yourself some tooling

and you have something really useful.

chriStephens (tongue firmly in cheek)

PS Yup, Quorn not as easy to set up as one would hope, but it makes another excuse for fiddling with tooling in an effort to improve it.
6 February 2012 at 20:13 #84062
Anonymous
Posted by chris stephens on 05/02/2012 19:26:59:

“Bin it” BIN IT are you mad….

Yes; why on earth would I want to be sane in a crazy world?

Andrew
6 February 2012 at 20:39 #84072
Sub Mandrel
Participant
@submandrel
Posted by Andrew Johnston on 06/02/2012 20:13:40:

Posted by chris stephens on 05/02/2012 19:26:59:

“Bin it” BIN IT are you mad….

Yes; why on earth would I want to be sane in a crazy world?

Andrew

He could keep them for shuriken, if he ever decides to become a ninja.

Actually, I was quite impressed by the thin parting tool idea.

Neil
6 February 2012 at 22:44 #84081
Harold Hall 1
Participant
@haroldhall1
Have a look here Wolfie

If a saucer wheel were available then the other face could be ground, first sharpening every other tooth, reversing, then the missed teeth, as John S suggests. Larger tooth saws are of course easier to sharpen.

Harold
6 February 2012 at 23:50 #84084
chris stephens
Participant
@chrisstephens63393
Or sharpen every other tooth but much deeper increasing the gullet size and halving the number of teeth, which will make it more useful.

chriStephens
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