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Issues holding T-type parting tool in AXA parting tool holder

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9t8z28

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#1
I am having issues keeping my .065" HSS parting blade held in my Knock-off Aloris AXA parting tool holder. When I tighten it down it wants to rotate leaving a gap on the top. It also rotates horizontally. I can fix the horizontal movement by moving the tool post but the tilt I cannot. I have thicker Somma T-type Parting blades and I dont have either of these issues with them. I have machined a horizontal groove the length of the holder so that the T-section of the blade can lay flat against the tool holder but it still kicks out on me. Any suggestions? Maybe machine a taper or angle on the wedge so that it pulls the parting blade in and down as I torque it down?

Here are 3 pics of the parting blade in the holder
 

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Nogoingback

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#2
One way to deal with that is to shim the bottom of the blade outwards. If you measure the blade thickness, you can determine how much
shim is required. I use a feeler gauge of the correct thickness.
 

rgray

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#3
That's a nicer blade than the chinese were planning on you using.
Need to machine a groove in the top of the channel so that style of blade will stand up straight when tightened down.
It's been years but I had to do that to mine also.
 

9t8z28

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#4
One way to deal with that is to shim the bottom of the blade outwards. If you measure the blade thickness, you can determine how much
shim is required. I use a feeler gauge of the correct thickness.
I already milled a slot on the tool holder to except the T so the shims will not fix the problem . This modification now matches the true Aloris.
 

9t8z28

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#5
That's a nicer blade than the chinese were planning on you using.
Need to machine a groove in the top of the channel so that style of blade will stand up straight when tightened down.
It's been years but I had to do that to mine also.
As I stated in my first post I have already done this modification
 

mikey

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#6
Odd behavior, especially since you ground clearance for the top of the blade. However, take a look here:

Screen Shot 02-26-18 at 08.40 PM.PNG

There is a radius in the bottom clearance slot and that might be canting the blade; possibly clean that up? The top of the blade in this shot looks asymmetrical - is that a real thing or is this just an artifact? Shouldn't have anything to do with alignment, though.

The only other thing I can think of is that the clamping dog that bears down on the blade is angled somehow. Maybe you can take a clean up cut where it contacts the blade and that might help.
 

Nogoingback

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#7
Have a closer look at how the toolholder is machined. You didn't mention what brand of holder you have, but some of the Chinese stuff
is pretty rough. Look for parallel or perpendicular surfaces, surface finish and whether the clamping nut is machined and moves properly.
What you may be up against is a poorly machined tool.
 

pstemari

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#8
Do you have clearance on both sides? You could mill a groove or shim it if necessary, but unless the sides are rubbing I don't know that it actually matters.

The parting blades without the t-top have a wedge cross-section, and I've found that those work fine despite not being shimmed.

Sent from my Pixel XL using Tapatalk
 

9t8z28

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#9
Do you have clearance on both sides? You could mill a groove or shim it if necessary, but unless the sides are rubbing I don't know that it actually matters.

The parting blades without the t-top have a wedge cross-section, and I've found that those work fine despite not being shimmed.

Sent from my Pixel XL using Tapatalk
As stated again, I already milled a slot. Shimming will not help. Clearance on both sides while making a cut? No its crooked. Being tilted forces the bottom to rub and that bends the blade making a convex or concave cut
 
Last edited:

9t8z28

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#10
Do you have clearance on both sides? You could mill a groove or shim it if necessary, but unless the sides are rubbing I don't know that it actually matters.

The parting blades without the t-top have a wedge cross-section, and I've found that those work fine despite not being shimmed.

Have a closer look at how the toolholder is machined. You didn't mention what brand of holder you have, but some of the Chinese stuff
is pretty rough. Look for parallel or perpendicular surfaces, surface finish and whether the clamping nut is machined and moves properly.
What you may be up against is a poorly machined tool.
All surfaces are square and parellel to each other and a good finish. The front side is a little rough but it doesnt make contact with any of the blade or wedge. Its an Aloris style from Little Machine Shop which are typically pretty good quality. I think the issue may lie in the wedge but I was hopping someone else had the same issue. As I torque it down I cannot see the wedge twisting but I guess I could check it with a DTI to see what its doing. I know I am not overtorquing it since I have had it get pushed back a few times from not being tight enough. The entire tool holder has been heat treated and is pretty tough material. I had a rough time machining the groove on the mill but its got clearance now
Sent from my Pixel XL using Tapatalk
 

9t8z28

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#11
Odd behavior, especially since you ground clearance for the top of the blade. However, take a look here:

View attachment 259871

There is a radius in the bottom clearance slot and that might be canting the blade; possibly clean that up? The top of the blade in this shot looks asymmetrical - is that a real thing or is this just an artifact? Shouldn't have anything to do with alignment, though.

The only other thing I can think of is that the clamping dog that bears down on the blade is angled somehow. Maybe you can take a clean up cut where it contacts the blade and that might help.
Yes there is a radius there. I thought about that but the pressure should be bearing down not forcing it to twist. The blade is symetrical. I will try temporarily filling the void at the bottom to see if it makes a difference
 

mikey

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#12
I should think that a radius at the base will cause some kind of distortion of the blade. Personally, I would take an end mill and clean that up, then look at the clamping dog thingy.
 

ddickey

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#14
You could make your own holder. I did for one of mine. Use the same Somma blades
 

petertha

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#15
I have the same holder. Made on Tuesday, not a Monday model like yours. Pretty sure the corner radius on the bottom is acting as the pivot point. Ideally this should be sharp, or better yet relieved with a counter-slit at some angle. But similarly, look at the quality of the corner in the top clamp & how well (or not) the clamp slides in its way. Either/or is acting on the corner of the blade. So aside from it rolling the blade out of position when tightening, even if it does feel snug, you are probably getting reduced blade support & thus rigidity - something you really want in a parting tool.

Checking for burs, ragged edges etc. is step-2 on Chinese tooling kits. (Step-1, of course, is removing all the brown schmeg. LOL)
I have these beautiful, mini precision vices from China. Fully hardened, ground on all surfaces, very accurate, dirt cheap. And then they put this POS ill fitting, hopelessly useless threaded nut assembly in that looks like something a rat chewed on. I don't get it. Why cut a corner like that & make something decent so bad? I'll spend the extra 3$ just finish the job! (end of rant)
 

whitmore

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#16
As stated again, I already milled a slot. Shimming will not help. Clearance on both sides while making a cut? No its crooked.
Well, there are three contact surfaces, side, bottom, and top. If the wedge weren't exactly horizontal level,
it could cant the T. Have you considered making another wedge from scrap, for the chosen blade (it
might take some tuning)? There's different width cutoff blades that might benefit from
other customizations, or from the original geometry.

I'm presuming that, like the flank, the wedge has milled clearance.
 

petertha

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#17
If you expand the image of this Shars, you can see a relief gap in the bottom to mitigate the radius issue.
http://www.shars.com/universal-parting-blade-tool-holder-7-type-007-oxa

Hmmm... maybe they don't all come from the same vendor.
I've heard similar complaints about offshore tool post dovetails. Some fit, some don't. I assumed it was QC but maybe there are knock-offs of knock-offs.
 

NortonDommi

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#18
If it is a tapered blade only one side is square to the top i.e. they only work one way around. In the photograph it looks like you have the tapered side against the toolholder, there is no way to hold the blade secure with this orientation.
 

9t8z28

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#19
I did some testing today with a .0001" idicator on the wedge and the blade. I put the indicator on the chuck side attached to the tool post. As I tightened down the wedge it moved towards the chuck .003". Now here's the interesting part which has me scratching my head, I put the indicator on the blade just above the wedge and when I torqued down the wedge the blade moved towards the chuck .030" !!!!
I then disassembled the entire holder. The vertical area that the wedge slides on is very rough. It looks like whatever endmill they used was not sharp And was plunged into the vertical surface. The vertical section of the wedge looks like it was machined with the side of a roughing Endmill. The rest of the surfaces are smooth. I can fit a .011" shim between the top of the wedge and its pocket.
Lastly I wanted to check my thicker parting blades and see if the moved or tilted as well. I have an1/8" and a 3/16". Surprisingly they both moved but stayed vertical. I'm at a loss for how to fix this. I am leaning towards making parting blade holders specifically for each of the parting tools. If I do decide to fix it I think the first thing I'm going to do is clean up the surface on the holder where the wedge sits and then make a new wedge. Thank you for everyone who took the time to reply and explain in detail. If and Ifwhen I if and when I make modifications I will report back here make modifications to it I will report back here
 

Bob Korves

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#20
If the movements are while tightening down the tool holder, then they should not be a problem while cutting. Make sure you measure the tool height and tool location after clamping it down, and if not correct, compensate and try again. Sure, it should really be fixed, but it need not cause you to do bad work. If the tool, post, compound. cross slide are all rigid enough and the cutter is in the correct position, then you are ready to go. Compensating is a PITA, but once known and properly adjusted for, the issues go away. Things often do move when tightening them down, and we need to deal with it.
 
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