New Project - AXA Multifix

[Susquatch]

@thestelster - How about a floating bushing - ie just there to hold it apart the right amount to get the boring bar in.

Can you post a few different views of this bushing you made? I can't really see how a split bushing could gall as you describe. I'm thinking maybe I don't really know what the split bushing looks like.

 

[whydontu]

My Multifix 1/2" nominal boring bar sleeve is 0.503" bore. No problem securing holding a 1/2" boring bar, never had any issues with tools spinning or slipping. Don't forget you have an enormous amount of clamping area, a 3" long x 3/4" bore sleeve has 7" of contact area on the tool. So a bit sloppy isn't the end of the world.

I use aluminum for my sleeves, easy to make them up as needed.

Cut a shim to fill in the slot of your undersize holder, chuck the holder in your lathe, and open up the bore a tiny bit.

 

[thestelster]

@thestelster - How about a floating bushing - ie just there to hold it apart the right amount to get the boring bar in.

Can you post a few different views of this bushing you made? I can't really see how a split bushing could gall as you describe. I'm thinking maybe I don't really know what the split bushing looks like.

Here is the boring bar holder on the right. It accepts 40mm tools. On the right in an ER40 collet chuck with 1" shank. In the middle is the split bushing. 40mm OD: 1"ID.

 

[thestelster]

My Multifix 1/2" nominal boring bar sleeve is 0.503" bore. No problem securing holding a 1/2" boring bar, never had any issues with tools spinning or slipping. Don't forget you have an enormous amount of clamping area, a 3" long x 3/4" bore sleeve has 7" of contact area on the tool. So a bit sloppy isn't the end of the world.

Cut a shim to fill in the slot of your undersize holder, chuck the holder in your lathe, and open up the bore a tiny bit.

Yes, I agree, but instead of turning it on the lathe I'm thinking to just hone the bore until the ER chuck fits.

 

[thestelster]

Or I can just slit right through the other side and have 2 pieces.

 

[whydontu]

Or I can just slit right through the other side and have 2 pieces.

PITA. Two-piece ones always seem to slide around, and you can't leave the tooling in the sleeve if you are swapping tools. I have a 3/8" boring bar for small stuff, and a 3//4" for big stuff and often have jobs that need both, easy to sit the bars in the sleeves and just have them next to the lathe for quick access.

 

[thestelster]

PITA. Two-piece ones always seem to slide around, and you can't leave the tooling in the sleeve if you are swapping tools. I have a 3/8" boring bar for small stuff, and a 3//4" for big stuff and often have jobs that need both, easy to sit the bars in the sleeves and just have them next to the lathe for quick access.

Yes, I agree. As soon as I mentioned it, I threw that idea out the window.

 

[Susquatch]

Here is the boring bar holder on the right. It accepts 40mm tools. On the right in an ER40 collet chuck with 1" shank. In the middle is the split bushing. 40mm OD: 1"ID.

The reason I wanted more photos was to understand how the part bends under load.

On looking at your picture, one side is cut right through and the other side is cut lengthwise about halfway through. So virtually all the unconstrained bending will take place in the remaining section of the half slice. Of course when constrained it will bend in the entire cylinder.

My own preference would be to drill and tap through the cross-section of the full gap and use a grub screw to pry the halves apart enough to get whatever you want into the bushing. Think like expanding a threading die for a bigger thread. Then remove the screws for the actual machining period. They are only there to pry the halves apart enough to insert or remove a tool.

As I said before, the other way to do it is to deliberately yield the half sliced section. It could be done with a small expander or perhaps even your shotgun tube mandrel. It shouldn't be too hard to do and would not affect the function one iota. If it is too hard to do, then the section is too thick anyway. Yielding the section once won't hurt it given the way it works. Especially if you are careful about how much you yield the section. Just enough to get a tool in and no more.

Another possibility is to slice through the bushing in a few more places. Enough so it stays together for convenient use but not so much as to constrain it for tool insertion. I think you could safely complete about 75% and perhaps much more of the length of that cut. Even keeping it intact at just one end would be better than leaving the entire half slit as is. But I'd try leaving a half inch at each end and just cut the center out. This should make it about 5x easier to insert a tool.

Although I'm not keen on the idea, you could also cut it right through from end to end and then use sliding pins and/or slip screws to keep the assembly together. Again, I'm not keen on this one but throw it out there in case it spawns a better idea.

 

[PeterT]

Oh you mean like this? LOL. In my case the offshore boring block QC was giving me grief. It was not really bored true & constantly had to hammer out the original C spacer, which didn't fit my tooling OD anyways. So I made a fore & aft pair of spacers completely parted into halves. It clamps up very rigidly now. You could make them with some grooves for an O-ring just to keep them mated for assembly.

 

[thestelster]

Well, sorry boys, I got fed up. I tried to expand the new split bushing using my shotgun barrel dent raiser and several sections of 3/4" type L copper tubbing. It would expand the bushing, but as soon as I released the pressure it went back to where it was. I reached the limit of the raiser. So I said @#$#%, I have exceeded my allotment of time devoted to this, so I chopped off a section of the bushing, expanded that section, held the slit open with some spacers, put the collet chuck in, and removed the spacers. Now the outside diameter is exactly 40mm, and the bore of the bushing is still 1.000". Now that tool is dedicated for that holder. It is what it is. I've learned a valuable lesson and hopefully I will remember it, which is getting more difficult with time!!

 

[PeterT]

It wasn't all in vain. Now I know what a barrel dent raiser looks like. Haha. Cool tool. How much rise can you get out of the anvil displacement?

So your ER tool accessory will be used to hold regular length tooling? (the shank doesn't look like it has a through hole to accommodate extended lengths like the bushing system?)

I mostly use insert type boring bars which have flats for regular toolholders. I don't use use my classic round bar with perpendicular (or angled) HSS bit much anymore. But looks like I have to break it out again for a special task - to widen the clearance trough on my radial crankcase which is ~15mm depth. I always questioned why the clearance was so narrow relative to the rotating parts. Just asking for trouble & maybe masking lubrication. I've rechecked the plans & my parts many times, I'm within a thou on collective assembly. But now in real life I really don't like it so need to either make or cannibalize a holding fixture & deal with this, Ugh.

 

[thestelster]

It wasn't all in vain. Now I know what a barrel dent raiser looks like. Haha. Cool tool. How much rise can you get out of the anvil displacement?

So your ER tool accessory will be used to hold regular length tooling? (the shank doesn't look like it has a through hole to accommodate extended lengths like the bushing system?)

I mostly use insert type boring bars which have flats for regular toolholders. I don't use use my classic round bar with perpendicular (or angled) HSS bit much anymore. But looks like I have to break it out again for a special task - to widen the clearance trough on my radial crankcase which is ~15mm depth. I always questioned why the clearance was so narrow relative to the rotating parts. Just asking for trouble & maybe masking lubrication. I've rechecked the plans & my parts many times, I'm within a thou on collective assembly. But now in real life I really don't like it so need to either make or cannibalize a holding fixture & deal with this, Ugh.

The anvil only moves out about 0.050-0.070".

The shank is treaded for a stop, I can't remember the thread, I think 5/8", but you can pass a 0.500" bar right through. I made a ER40 Collet chuck for the lathe, and bored it out to take up to 3/4" bar stock, but that chuck has a 1.250" shank.

 

[thestelster]

An Update:

I've been using the lathe with the the new Multifix QCTP, and I have to say, I love the convenience of quick change, and its rigidity, and its ability to quickly adjust for different leads or clearances. One thing that bothered me a bit, not in the system, but the sizing, is that the tool holders had to sit fairly high on the post for the cutting tip to be on center. My tools are all 3/4" shanks.

 

[whydontu]

An Update:

I've been using the lathe with the the new Multifix QCTP, and I have to say, I love the convenience of quick change, and its rigidity, and its ability to quickly adjust for different leads or clearances. One thing that bothered me a bit, not in the system, but the sizing, is that the tool holders had to sit fairly high on the post for the cutting tip to be on center. My tools are all 3/4" shanks.

Never had a problem with mine, no noticeable increase in chatter or loss of rigidity at any mounting height. If you’re concerned, maybe make a 1/4” plinth to go between the centre cylinder and the tee nut?

 

[thestelster]

It was bothering so much I decided to put a spacer between the tool post and compound. 1/4" spacer would be perfect. Of course I didn't have 1/4" HR, but I did have 5/16". So I said to myself, self, why don't I surface grind the one side, and then fly cut the other side and then grind to size. So I put the plate right on the magnetic vise, ground the one side and removed it, checked it with a square for flatness, and you know what?......gaps of light in sections. Hmm?! Ok let's turn it 90° and try again. Hmm...same thing. Obviously, the magnet chuck was strong enough to bend the hot rolled plate to flatten it, and when released, it bent back. I decided I needed less magnetism. So I put several sheets of card stock between the plate and magnet, and of course blocked it off so the plate wouldn't go flying. With the card stock, between, I was able to move the plate with a little force but not much. I only took light passes off 0.0004" per pass. After several passes, all was good, and plate was flat, no gaps of light.

 

[thestelster]

Ok, now one side is done, let's fly cut the other.

 

[thestelster]

After flycutting, bored for center post, drilled, countersunk, tapped, 1/4"-28 flat head socket screws. Attached the plate to the compound, put the compound on the surface grinder, and ground the plate.

Put everything back together, installed tool holder with tool, and adjusted for center. I'm a happy camper!!

 

[thestelster]

This is today's recent delivery for the AXA Multifix QCTP. 2 boring bar holders with, what they call prisms, which is a spacer for smaller diameter boring bars. These holders will only hold round tooling.

 

[thestelster]

I have been drilling with the drill chuck mounted on Multifix QCTP for a little while now. I am extremely happy with set-up. The Multifix has a tool holder for boring bars, 40mm in my "B" size. Though, I do not have 40mm boring bars, I can utilize reducing bushings for smaller boring bars, or what I've done previously, made a 1" bushing to hold an ER40 straight shank collet chuck. But you can also get morse taper bushings to hold those type of tools. I have an MT3 and an MT4 bushing. Currently I have my small (0-10mm) Albrecht drill chuck mounted in the MT3 bushing and mounted in the boring bar tool holder.
The beauty of this is that the drill chuck arbor is tanged, and the MT bushings will accept the tang. Once assembled, there is no way that you will spin the chuck, as opposed to it being mounted in the tail stock, which (at least on my lathe), has no provisions to accept the tang. As you can see in one of the photos, the chuck spindle has spun several times (due to a damaged tail stock bore (which I remedied in another post.))

I can now quickly drill, under power feed; I don't have to clean the lathe bed, then squirt way-oil onto it, then drag the tail stock up and down the lathe bed; I don't need to tighten the tail stock, drill, loosen the tail stock, move it backward, change bit, push forward, tighten it, drill, repeat. Max travel of my tail stock spindle is 4", but I only go 3" because it sticks out so much. Using the QCTP, I have 50"!! so no more repositioning of the tail stock when drilling long holes.
Once the center height is established, it literally takes a couple of minutes to dial it in the x-axis with a DTI, and a couple seconds if you have a DRO. Changing tooling: loosen the two bolts of the split tool holder, remove the MT busing with tool A, insert MT bushing holding tool B. Tighten bolts.

I think this is one of the best uses of a QCTP.

 

[Susquatch]

I have been drilling with the drill chuck mounted on Multifix QCTP for a little while now. I am extremely happy with set-up.

My tailstock has an MT3 Taper with the tang provisions so I am happy using it to drill with. It is also 4 inches, but not with a tang. The tang will self eject at 0.75 inches so I lose 3/4" of travel. It has never been an issue and even if it was, I love the auto eject feature so I'd simply live with it.

I have an MT3 tool holder that came with my lathe that I've never used. I will have to try it your way just to get a feel for your joy.

One of the concerns I would have with using a tool holder is concentricity to the spindle. It's easy to adjust side parallelism, but how do you adjust the vertical? Just pray that it's ok?