Slitting saw advice

[Tony Pratt 1Participant @tonypratt1]

None of the tools we use in engineering are toys and should be respected at all times, eye protection is the order of the day! Use sharp cutters and think what you are doing.

Tony

Edited By Tony Pratt 1 on 17/02/2014 17:24:07

[Tony Pratt 1Participant @tonypratt1]

Double post

Edited By Tony Pratt 1 on 17/02/2014 17:23:33

[GarryCParticipant @garryc]

Hi Bob

I'm going to dare to partially and respectfully disagree with Tony. Having grown up from a young age working with lethal machinery you develop a sense for these things – just eye protection is not enough for this, especially as you sound to have no experience using them yet – but I would say better safe than sorry at all times. It takes no longer to reach for a full face mask than it does for the safety glasses – my full face mask cost about £10, the slitting saw is the only thing I have used it for and I wear safety glasses at all times for everything else…

Cheers.

Allan.

[Bob PerkinsParticipant @bobperkins67044]

Thanks all for the advice. Perhaps like many coming home from a work environment where H&S is applied to the highest standards, standards in the home shop leave a bit to be desired. Am I the only person on the forum that taken the safety guards off their lathe, and mill, oh and the table saw. I think the guy on sky, who's hame escapes me, used to say that the guards are removed for filming purposes! I do have a selection of safety goggles but perhaps will invest Ina visor.. I did my apprenticeship with an excellent guy who I will be forever grateful to for trying to impart many years of knowledge and experience into a teenager. One piece of advice was to always use your less dominant hand the putting fuses back in. I'm not sure that type of H&S risk assessment would be acceptable today!

Im into some major DIY at present so the slitting saw advice is yet to be put into practice.

Bob..

[Neil WyattModerator @neilwyatt]

I would say a slitting saw running fast enough to spray swarf is running far too fast.

Neil

[Oompa LumpaParticipant @oompalumpa34302]

Posted by Bob Perkins on 17/02/2014 20:38:54:

Am I theonly person on the forum that taken the safety guards off their lathe, and mill, oh and the table saw.

Nope. And you can add Chopsaw Hand held Circular Saws and Polishing machines to that list. Chop saw is shortly going in the crusher, it is quite dangerous.

graham.

[GaryMParticipant @garym]

Slitting saws remind me of the Kung Fu throwing stars that enjoyed a brief (thankfully) popularity in the seventies when I was at secondary school. As you can imagine nobody at school was wearing any protection.

Gary

[julian atkinsParticipant @julianatkins58923]

ive never used a slitting saw on an arbour. i always use a junior hacksaw with a new blade on miniature loco eccentric straps. ok they then need cleaning up in the vertical slide or mill, but that doesnt take very long. then soft solder together, drill the bolt holes (tight clearance fit, i usually turn up fitted bolts anyway), then machine to width both sides and bore to ID to a plug gauge. when holding in the four jaw be very careful you dont apply too much pressure with the jaws. then heat up to melt the soft solder and wipe off any excess. this was pretty standard as per LBSC . i have an old iron for clothes ironing i use for soft soldering such jobs – nice flat surface.

i usually bore mine dead on then apply engineers blue and scrape to fit the eccentric sheaves. btw i always fit proper bolted on eccentric rods – and i dont really like the combined rod and strap casting in bob's initial pic, though i did do a Stuart Turner 10 that way years ago. it will be easier to machine plus look much better with a bolted on eccentric rod.

cheers,

julian

[Ian S CParticipant @iansc]

With the Eclipse Junior hacksaw you can if need be cut very accurately by clamping two bits of 1/4" steel, one each side of the cutting line, with a firm sliding fit for the blade, use a new blade, lubricate it well, either oil or candle wax. Don't push it, just let the saw do the work, or do as I did and build a little power hacksaw. Ian S C

Edited By Ian S C on 18/02/2014 11:31:54

[Tony Pratt 1Participant @tonypratt1]

When I was an apprentice all the horizontal milling M/C’s were fully guarded but some idiot still managed to get his hand near the cutter and lose some fingers! If you do not respect tools and machines no amount of guarding will prevent injury.

I totally agree with guarding grinding wheels as they can be unpredictable but as a Toolmaker I found guards intrusive on manual machines. The advent of CNC machines in industry has taken guarding to a whole new level and quite rightly so.

As I said before your eyes must be fully protected at all times as they are so fragile and once they are gone they are not coming back.

Tony

[Steve WithnellParticipant @stevewithnell34426]

H&S tips

1. If you must wipe the soldering iron on the leg of your overalls, make sure they are cotton, not polyester (ouch).

2. If using a slitting saw in an arbor, ensure the keyway slot is NOT used, if the saw jams, it can then slip rather than fracture (ouch)

Steve

[steveteeParticipant @stevetee]

Over the years I worked in engineering I must have sli tsawed thousands of items. Most jobs came in batches of 100 and slitting rocker arm eyes was a common job. Once you had broken a couple of slit saws the sound of the foreman shouting was enough to focus the mind such that you found out how to do the the job quickly enough to make some piecework and slowly enough to not break any cutters.

What I learnt was this . 1. Never use a key 2. Do the arbor up as tight as you can ( 2 apprentices and a twelve foot scaffolding pole usually does the trick) 3 Never use the feed, stand at the end of the table and carefully feed the cutter in by hand, if it does snag , quickly wind it back to free the snag and carry on. The only other tip was to get the batch done before the inspector came round again, only to find that the cutter had wandered half a thou off centre causing him extreme distress. I never saw a guard on any of the machines on the bay I worked in, no time for all that , we were on piece work. All gone now https://www.youtube.com/watch?v=i3UVz4F3wyw

[Michael GilliganParticipant @michaelgilligan61133]

stevetee,

If you don't have it already …

There is apparently a free booklet available about Mirrlees site history

see here

MichaelG.

[Bob PerkinsParticipant @bobperkins67044]

Sorry all, back to slitting. I hope to be able to find a bit of time at the weekend to open the slitting saws that Santa bought me and have a go at my 10V crankshaft. Just a bit of advise from the wise on how I should feed the saw into the workpiece. I have tried to sketch my understandings of the options in the PERKO-CAD sketch, which are:

1) plunge cut

2) up cut

3) down cut

[Michael GilliganParticipant @michaelgilligan61133]

Bob,

I would use (2)

MichaelG.

[ian cableParticipant @iancable23486]

without any doubt number 2 ,the other 2 are called climber milling which allows the cutter to grab the work piece and try and drag it in .like others have said slow speed personely I use between 60/100 rpm on small up to 2" then half that for large ones, also high speed will just burn out your 10 quid cutter ian c

[JAParticipant @ja]

Briefly

1. Perhaps, slow feed with great care. Best avoided.

2. Yes. This is the normal way to use any cutter

3. NO. This is climbing and will probably break the saw. Simply the saw, or cutter, will try to climb over the work and put excess loads on the tool and machine. In a few cases, such as some high alloy steels that work harden, climbing has to be used.

Cutting details. Assuming the crank is mild steel I would use a maximum cutting speed about 80ft/min (400mm/s). For a 3" slitting saw this would be 100rpm. The feed should be slow, very slow. I do not take a deep cut when using a slitting saw, usually using less than 1mm depth. OK it takes time but I am not on piece work. Use cutting oil/coolant. If in doubt reduce reduce speeds and depth of cut. If the crank is cast iron lower the speeds and do not use cutting oil/coolant.

JA

[Roderick JenkinsParticipant @roderickjenkins93242]

In general I think 2 is best but I would feed in the other direction so that the backlash is taken up by the saw always pushing against the leadscrew. Of course, I'm not sure if the arrow in your diagram refers to the saw or the job but the principle is the same: always feed so that the pressure from the rotating cutter is pushing back against the job moving towards it.

cheers

Rod

[Bob PerkinsParticipant @bobperkins67044]

Thanks all for the feedback. As usual one question leads to at least one more. The Conrod is brass, and I have to cut through a thickness of 8mm. Will a slitting saw do this in one pass with a slow feed, or will it need several passes with a shallower cut?

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Bob Perkins on 28/02/2014 13:35:38:

Thanks all for the feedback. As usual one question leads to at least one more. The Conrod is brass, and I have to cut through a thickness of 8mm. Will a slitting saw do this in one pass with a slow feed, or will it need several passes with a shallower cut?

.

Bob,

It should be fine in one pass:

Do bear in mind that the combined effect of the number of teeth and the diameter of the blade will determine the appropriate speed.

I would suggest experimenting on a bit of scrap Brass first, to get a feel for what you're doing.

MichaelG.

[Clive HartlandParticipant @clivehartland94829]

Bob, I always initially do a small cut and then start again with another cut, the idea is that the initial cut will stop the slitting saw wandering. 8mm sounds a lot but on Brass not so, slow manual feed and do lubricate it with kero or WD40. The frequent lub. application will also flush out the swarf and keep it cool.

Clive

[Stuart BridgerParticipant @stuartbridger82290]

Bob,

My 10V conrod was my first serious use of a slitting saw.

I may have been over cautious, but I took it VERY gently. Multiple shallow cuts with slow feed worked fine for me.

It did take time,but there were no tears.

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