Setting up slitting saw for round stock?

I put the saw mandrel in a lathe chuck and made a block with a hole and setscrew to mount on the cross-slide. Did this to slit the threaded end of a bolt - it has a countersunk hole lengthways through it and when a smaller screw is thightened it locks the threads. This bolt is the mount for a ball-turning attachment; I wanted to be able to lock the mounting bolt at the right clearance without having it c*ck or move sideways, so a locknut and a setscrew were both out.

I had to thread the hole through my block, but you don't need that. If you wanted to get fancy you could make a shouldered sleeve with your setscrew holding the stock, drill a hole in the shoulder, and two holes in the block for a pin to set your 90 degree cuts.

Thanks for your ideas - it's always the way that there's more though and effort needed to be put in to make the jig than to make the device in which you're interested!

Assuming you are using a vertical mill so that the slitting saw is horizontal, and the work is fixtured horizontal (vee block perhaps):

a/ Measure height of top of stock with vernier height guage, subtract half the stock thickness, and add half the slitting saw thickness - set the height guage to the resultant figure.

b/ Adjust quill of mill so top of slitting saw just touches the height guage and lock the quill.

You now have the slitting saw bang on centre of the work.

AWEM

If you're making more than half a dozen it'd be worth it.

This trick assumes you have the slitting saw in a vertical mill, the bar is horizontal, and the slitting saw teeth are straight (i.e.. not staggered like a wood saw blade). Adjust the position of the bar and saw so that, by eye, the blade is just about touching the fattest part of the bar. Interpose a vertical

6" steel rule between the bar and the saw and move the table to very gently pinch the rule. Unless you were lucky and set the saw exactly on the fattest part, the rule will no longer be vertical. Adjust the hight of the saw until the rule is truly vertical - you will be amazed at how accurately the blade is then at centre hight.

I have to make up about 14 such plugs.

(Although a nagging voice inside suggests that I should also consider the "Binding Post" approach together with spade terminals)

Damn! I knew I should have purchased that digital height gauge at the club sale, especially as it was only £10!

The only difficulty otherwise with what you suggest is the tendency of slitting saws to bend under the slightest lateral force, but thanks anyway.

The simplest way I know to locate a line on top of round stock is this: (BTW, you don't have to switch from vertical to horizontal modes to make it work.)

Mount the stock parallel to the mill table, and dead-level, with the "working end" solidly in your mill vise, and enough overhang for the slitting saw to clear the vise when you're working on the _side_ of the rod.

True up the work with your longitudinal travel, so it's _pretty_ good. A thou. is OK, you don't need it to tenths.

With any-ol' side-cutting bit, slowly close in on the side of the work until the bit just kisses the metal. Then make a longitudinal cut for however far you want the slit to go.

You've now marked a line and flat that is parallel to the axis of the rod, and perfectly centered on the horizontal diameter of the rod.

Without removing the work from the vise, you can switch to your slitting saw, and true up the saw to the line you've just marked -- then cut.

LLoyd

Doesn't need to be "exactly" because it's the diameter that is more critical than the position of the slot - I suspect even as much as just less than the thickness of the slitting saw off centre would not be a problem.

I made a connector (female as opposed to your male) for an old radio by slitting brass tube. Hacksaw and vice produced good enough accuracy for an excellent operational performance.

Steve

How about making a square fixture to hold the round part with two slits to guide the saw blade?

I have found that a good fret/jewelers saw very handy for cutting small items. I find it very difficult to cut 1/8 drill rod with a hacksaw but easy with a fret saw. They cut faster than you expect.

Lay the round bar stock in a Vee and put it under the saw so the saw just touches the highest part of the rod. As long as the stock is round you'll have a tangent to the diameter and all you need to do is start slotting, half in two. There used to be lots of banana plugs for sale on eBay and hamfest, quicker, easier, and cheaper than DIY.

Set it on center, set your depth of cut, set your speed and feed, cut. What more do you want?

That's the question, how do you set it on center?

Hi Hank,

It seems it's not how, but how well. The how is trivial. The how well is more a matter of a stock of ¼ inch which is sacrificed to lumbering gross tools. Modern machines just make errors faster when it is obviously within the scope of simpler hand tools and jigs. More time has been expended in the sterile scribblings of what could be, in place of actually getting it done.

73's Richard Clark, KB7QHC

That's a good idea - I must otherwise admit to being lazy when it comes to the possibility of NOT doing things with a hand saw!

The biggest off-the-shelf bananas that I have seen are

4mm. In any case, doing things for yourself is what differentiates the Radio Ham from the CBer!

How do you propose to set it on "center"? (English speakers spell that as, "centre"!). That is the nub of my enquiry.

Well, if you have "stock", and it's a small thing of which you're making many, you get a method that allows both measured increments and a locking system. You do a test, and adjust, so that once it's good enough, you just shove the stock in and slice it.

If it's a one-off that has much time/money/work already into it, you use the same arrangement but plan and measure as best you can first.