Slitting & Jeweler's saws - what are their uses?

[Mike Burdick]

I need to make a number of slits on the side of a round piece of 4140 annealed steel that is 5/16" thick. The slits need to be 1/4 inch deep, 5/16 inch long, and 1/16 inch wide.

I was wondering if a slitting or jeweler's saw would work. If so, do they stand up very well and what precautions do I need to be aware of so I don't break the blade?

Thanks.....Mike



[This message has been edited by Mike Burdick (edited 02-18-2003).]

[SGW]

Sounds like it ought to work. Generally, I think jeweler's saws have finer teeth than slitting saws.

Probably he main thing to watch out for is speed. With a 4" diameter saw, 100 rpm is plenty fast, and you might want to be slower. Given the cuts you need to make you can probzbly use a 2" diameter saw, in which case 200 rpm would be okay.

Lubrication helps. You can (with appropriate caution) slather on cutting oil with a brush, if you don't have mist or flood cooling. I use mist, and find that the airstream has the additional benefit of getting the chips out of the way.

Go easy and you should be fine.

If you're cutting 1/4" deep on a 5/16" dia. round rod, you won't have much support left, so be sure the rod doesn't bend on you and pinch the blade. I assume you're cutting across the rod; if lengthwise, I'm not sure how you plan to do it, as you'll have the entry/exit curvature of the blade.

[gvasale]

slitting saw is the answer. Far easier to use with much better results, uniform straight cuts. Done easily with a mill or lathe. BTW, S. Larose has jewelers blades only to .0236 (one source I use). You can get slitting saws in the size you need. Also, if you were not referring to the miniature "hack saw" style blades, ignore the first half of reply.

[wierdscience]

If you are going to do this in a milling machine make sure that the mill spindle is planed in perfectly prependicular to the table.If it is off even a little it can cuase the saw to dish and affect your cut accuracy.

[Thrud]

Mike
Generally the jewellers saws are use for slitting sheet goods such as gold and silver. A slotting saw should be used as the are hollow ground for side clearance and have fewer teeth.

If you are stuck you can use the jewellers saw, but if you are ordering one in, order the slotting saw.

The same principles for tooth count versus material thickness used in band or hack sawing should always be taken into consideration.

[Mike Burdick]

Thank you all for the help! I've got to order one so I suspect that when start using it I'll have more understanding of them.

One additional thing.....Thrud, what is the principle for tooth count versus material thickness you refered to?

Thanks.....Mike

[Ian B]

SGW,

(or anyone else...)

You mentioned a mist cooling unit. I've never seen one. Is this something that the average HSM could make up for himself using a shop air compressor, a tank and a pump? It sounds like you get good cooling without large volumes of cutting fluid sloshing around the place.

What kind of fluid do you use, any problems or advice? My application would be on a turret mill.

Many thanks,

Ian

[SGW]

Check "the usual suspects" list of machine tool catalogs (MSC, www.mscdirect.com Travers, www.travers.com , etc.) and you'll see mist cooling units.

Some are better than others. I've got one made by Bijur, but lately Bijur's prices have gone from fairly high to completely astronmical, so I wouldn't recommend it unless you can find a used one at a sane price.

In principle, they're an atomizing unit that spray a water-based coolant (typically 25:1 to 50:1 dilution) in an airstream. Ideally, there is NO visible mist, or very little. The cooling comes from the refrigeration effect of the liquid evaporating into the airstream. If you stick your finger in the airstream and then slowly turn on the coolant flow, you can feel when this happens.

It's a fairly non-messy setup. Although the coolant has anti-rust additives and all that, I find it's still a good idea to clean up afterwards. The coolant reservoir has a tendancy to grow fur after sitting for a while, so there's an ongoing maintenance issue.

I'm not sure how well the cheap units operate. The Bijur pressurizes the coolant tank, but the cheap units use a setup like a siphon-feed paint sprayer to suck up the coolant, I think. Not that the Bijur necessarily always works well, either.

[JCHannum]

To really confuse the issue, there are slitting, slotting AND jewelers saws. They can all look pretty much the same.
Slitting saws are hollow ground for side clearance, and can be used in deep slots or for cutting off. As they increase in thickness, they eventually become side cutting mill cutters.
Slotting saws and jewelers saws are flat, and are mostly used for slotting, as in screw slots. They can be used for cutting sheet and tubing. The main difference is that jewelers saws are much thinner and have finer teeth.
Slitting saws can be used for slitting and slotting, while slotting saws can only be used for slotting and slitting. This should clear it up.

[Thrud]

Mike
Pick a tooth count that give at least 2 teeth for material thickness. This cuts (pardon the pun) excess vibration and chatter between the blade and material (less tendency to grab as well). SO when slitting sheet goods you use a saw with higher tooth count than a solid block might.

[Stepside]

If using mist cooling, make sure you don't over do it. It won't hurt the part but it won't help your lungs.

I use a Trico "Micro Drop" that uses a great deal of air compared to the fluid. It works well. My choice is flood the sucker and clean up the machine later.

When sawing, lock everything you can, and proceed at a rate that allows the swarf to clear. When purchasing a slitting saw, order two. This will keep Murphy away, because having a spare should keep you from breaking the first one.

[crypto]

Mike,

One of the most exciting accidental discoveries that I have ever made in my machining career occurred when I applied an anti-seize lubricant to a slitting saw. I was cutting a 3/8"deep x 1/32" wide slot in copper.

I could hardly believe what I observed. The thick lubricant simply did not allow the chips to stick to the gullet of the tooth. Chips come showering out of the cut. Cutter does not jam up in the cut.

I began to experiment. I then made a cut 5/8" deep x .035" wide in a piece of stainless. An experimental tool that required a 0.006" wide slot 1/4" deep was also cut using this lubricant.

The clincher is that all of these cuts were made in ONE FULL DEPTH PASS.

I used Sta-Lube Silver أ…nti-Seize and Fel-Pro أ‡5-A (copper based) anti-seize lubricant. Both of them gave similar results. They can be purchased thru tooling catalogs (MSC) or auto supply shops.

It is a rather scary experience to see these cutters plow thru the cut for I can't tell you how many broken cutters I have had to dig out of slots in 50+ years of machining. I still hold my breath everytime I use this process.

[Mike Burdick]

crypto,

Sounds like a very good idea! I wonder if it would help on parting. Have you (or anyone) ever tried this?

Mike

[lynnl]

Oscar, is that(those) stick lubricant? or a fluid?

I recently bought a stick lub at Home Depot made by the Oldham saw blade company. Wonder if it'd work similarly? It says "..for wood, plastics, metal, etc. etc...)

[This message has been edited by lynnl (edited 02-20-2003).]

[crypto]

I don't believe it would help in parting. The lubricant would be immediately scrubbed off by the emerging chip.

The lubricant, of a thick grease form, is in a small screw top can which has a brush attached to the cap. I believe if you visit any auto parts store and ask for anti-seize they will have it. Just smear it on the cutter and keep an eye on it as it cuts to make sure that your cutter's teeth don't run dry.

Don't buy the spray can form. I believe this would make a heluva mess on your vise and job. Travers catalog has it in a brush top 8 0z can-(81-006-510) $10.49. Enco has LOCKTITE C5-A (505-1318) $8.30, this is the exact one I have used.

Back to the parting question. One of the problems encountered in answering questions on this web is that the old timers and journeymen probably are operating on full size machines. My LeBlond weighs approx. 3,000# , the Clausing 1500#. These husky lathes permit the proper approach to parting which is, don't go slow! Pile into the cut, go fast enough and feed fast enough to allow the wiping action of the flow of chips to keep your cutting edge free of any buildup of chips. I usually cut dry unless I'm pretty deep into a cut.

I have 9" Logan and I HATE TO PART ON THAT LITTLE GUY. I know I'm going to have a chatter problem, It just doesn't have the necessary mass to hold the cutter rigidly into the cut.

Many years ago at a machinery show I saw an impressive parting tool demonstration on a small South Bend bench lathe. The cutter, which was hooklike, like a linoleum cutter's knife, was mounted at the rear of the crossslide. It cut on the backside and produced a downward thrust on the job. With the current great interest in homeshop machining its too bad that someone is not making a similar tool. I'll bet there would be a market for it.

It's tempting to think of trying to make something that would duplicate that tool.

Oscar