Clausing 5914 - Tool-slide saga

What!? You are making cutoffs with 12 x 12 mm bits!? You don't have to wonder if there is chatter, noise and vibration. 4mm wide for a 50mm deep cut is OK, but the bit has do be *considerably* higher. My HSS-blade is 2,7 mm wide and 11mm high. Good for 40mm (diam.) cutoffs. The carbide inserts blade is 32mm high and the width is 3mm. That is OK for

100mm diameter cutoffs. Get real tools.

Considering the leaded (supposedly) steel with a weld. Can't be, can't weld leaded steel. It makes bubbles while welding.

Nick

No. The cutoff blade is 3/32 inch (2.4 mm) wide, and chattered instantly, right at the surface of the rod.

The chatter begins right at the surface.

The blade is ~12 mm high by 2.4 mm wide, and works OK in 5/8" (16 mm) stock, but failed for 35 mm diameter stock, but by your experience it should have worked. As discussed, I think it's some combination of loose dovetails and the Rube Goldberg setup holding the cutoff blade.

You are implying a required ratio between blade width and stock diameter, which makes sense. Do you have a source for such a ratio?

What we do know is that the ratio exceeds 40/2.7= 14.8:1 for the HSS blade and 100/3=33:1 for the carbide insert blade.

They are real. Loose dovetails will undermine the best of tooling, so the dovetails are getting the attention. Followed by a better cutoff tool for sure.

The bar was not welded to anything, but there was a frozen weld puddle at one end. Perhaps they were testing, saw it bubble, used something else.

Joe Gwinn

So I misunderstood that. Sorry. Learning how to part off initially takes some nerves and maybe some blades you will break 'till you got it. It has been said many times: Do not try to slowly part off. If the blade quiiiiks, feed quicker. Don't start with scratching around, but *feed*. Increase feed until you get a nice chip and keep that feed *constant*- That means that a automatic cross-feed is the best. If not available, use both hands to turn the crank. The third hand is used to lubricate. :-)

That should work too, depending on the material. Lubricate but don't hesitate.

No source. Experience. Also depends on the material. I wouldn't use my HSS-blade on 40mm aluminium. I had too many bad experiences. :-)

It is more the stickout (to reach to the center of the bar) and height (rigid) of the blade. If you have a bore in the bar, you can use a lighter blade (obviously). Only the depth of cut and the required stickout therefore counts.

Not that much. The sloppiness in the guides doesn't count *that* much, because cutting forces will move the parts where they have to be . What counts more is how rigid things are. Note that there is *no* contradiction between sloppiness and rigidness. As long as you keep the feed constant, the cutting force is constant. As soon as you feel uncomfortable and reduce the feed, things will start to move and start to chatter.

A friend has the same carbide insert blade I do have (but a lighter lathe) and he has broken already two of the holders, I'm still using the first insert (on the first holder). I really don't know what he is doing (I'll have to visit him to see). But when he visited me and asked me to show it he saw that they work. Coolant on, cross feed on and off it goes. More feed? If you want! Faster? If you want. Even faster? No, look at the chips, they are starting to look bad, that's the limit. Slower? No, chips are getting bad, that's the lower limit. Without coolant? Not with this RPM, but with less, yes. You see, you have to try it. But blades aren't that forgiving. .

Nick

OK. I think DoN's lathe is large enough, but not the 5914.

I haven't broken any blades yet. But it's a sure thing.

I tried pushing harder, and it only shook harder. Unlike with the 5/8" bar. I was also having chatter problems with ordinary cutting bits, so my suspicions turned to loose joints.

I think that the fact that the blade is so far out from the toolpost body, thus increasing the lever arm, is a cause of multiple problems. I bet many problems will go away when I get a better toolpost.

OK.

Except that the compound and attached toolpost visibly tilted leftward under cutoff loads, even when cutting the 5/8 bar. This really had to be fixed, and things improved greatly after the dovetail was tightened.

Part the tilting was also due to that large lever arm.

He may be spinning the work too slowly. I made that mistake at first, and had problems with grabbing. In retrospect, part of the problem was probably due to the toolpost tilting, but running faster nonetheless helped greatly.

Joe Gwinn

I don't think it is something to be ashamed of. At least, I have broken a few too. HSS, that's cheaper. :-))

If you had the same stickout (not enough for 4" to part off) there should be no difference.

Oh! If you look at the bed in a cross section, you do have 3 (yes, 3 not just 2) guides. Two on top (one being roof-shaped) and one on the rear

*bottom*. Here, a guide of the saddle is gripping downwards (can't express better) and prevents the saddle's rear from lifting off of the bed. You really have to bend over your lathe to see that guide. Got me? Check that guide and adjust it.

AXA AKA Multifix rulez! :-)

Outch! When parting off, move the top slide as much as possible to the

*right*. This way, it gets more/better support. But watch the jaws!

No, he broke his next holder after my instruction and show and tell. But he didn't blame me for that. :-)

Nick

My objective is to not break the lathe itself. But blades are expendable.

The real problem is that when a blade breaks, whatever one is cutting off is often ruined in the process.

You mean the hold-down plates and the carriage clamp plate. These are under the ways and face up. The hold down plates are probably OK as they are adjusted using shims, and so are pretty much user-proof. I do use the carriage clamp when cutting off, and it does seat firmly. But I will still look, just to be sure.

Ja! But they are pretty big. I'm leaning towards Aloris BXA.

I did this, including getting too close to the chuck, but it didn't help. Fixing the loose joints seems more direct.

Good. But you will need to watch him try cutoffs before you will be able to figure out what is wrong.

Joe Gwinn

Very good! ;-)

That's part of the learing process. No pain, no gain.

If the hold-down plates are on the rear, yes. The carriage clamp is on the front. I mean the similar setup on the rear. I suspect that your carriage's rear is lifting off. Why? With a small diameter, the cutting force is projecting within the two guides of the bed. With a big diameter, the force is moving outside of the guide and thus tilting your carriage (lifting the rear).

What I do with deep(er) cuts is to initially clamp the carriage and later (after 1/3 or such) loosen it. You also have to pay attention that the blade is dead at 90° to the spindle. An easy way to check this is to move the carriage to the left until the blade's side touches the chuck's face. No, not with the lathe running . Then you see how well it aligns or not.

There's one size below size "A". It's "Aa". But you have to check tool height. I have similar ones to the Aloris on my small lathe. They aren't good with repeatability. If you remove it and reinsert it, it is on a slightly different place. The Multifix really has an repeatability of 1/100mm. I tried this.

Will happen when I help him install his VFD. But first, he has to help me bring down my replacement lathe. No, I didn't break it! It simply was well out of specs, so I finally got a new one yesterday.

Nick

True enough.

I'm not sure that this could be the mechanism, because even the larger bar is well centered between the two rails of the way. Nor can I imagine the person that allowed the dovetails to become so loose concerning themselves with something like the hold-down plate. In fact, I doubt that they could find such a plate in broad daylight.

But it's easy to check that the hold-down plates are correct.

OK. By the way, the carriage clamp plate works on the front bed way rail, and so would not much help if the back hold-down plate were loose.

I've been using a little square between the bar to be cut off and the blade. The 5/8 rod was in a collet, with no easy reference surface.

Hmm. Another difference in rigidity. The 5/8 rod was in a collet, while the 1.35" rod was in a 3-jaw scroll chuck.

I'm sure that there is a recommended size for any given lathe. The BXA is what Aloris recommends for the 5914.

I believe it, given the inherent averaging from clamping two zigzag surfaces together. How bad was the Aloris clone repeatability?

You wore it out? I bought mine pre-worn.

Joe Gwinn

Two vectors of cutting force during parting off:

1.) pointing vertical downwards from the tip of the blade 2.) pointing horizontal outwards (along the blade) from the in-feed force

If you add the two vectors and the resulting vector is not pointing between the two rails, the rear will lift. To prevent that, there is a 3rd guide (rear, downside).

Nick

Right. I'm saying that given the small diameter stock (compared to the spacing between way rails), it could be hard to arrange this. But I'll look.

Joe Gwinn