# Can't tighten down my quick change tool post due to Grizzly's poor design



## stioc (Apr 29, 2019)

I have a AXA QCTP that I purchased from Little Machine Shop but I can't seem to tighten it down well. The reason why I can't tighten is because the tool post stud that came with the lathe (LMS supplies an adapter sleeve that threads into this stud) doesn't seem to have a locating pin nor splines nor any other kind of a stop https://www.grizzly.com/parts/Grizzly-TOOL-POST-STUD/P4000908 so as I tighten the QCTP nut down it starts to spin the whole stud. Upon doing research it seems the older versions of the 9x20s came with the bottom of the stud splined. Not anymore 

To fix this I'm thinking of cutting a flat slot across the bottom of the toolpost stud and a matching slot on the compound body underneath then welding a section of a drill bit into the slot on the stud to sort of make a T. That will prevent the stud from turning once the drill bit section finds the  matching slot in the compound body. Never welded a hardened drill bit before but should weld like any other steel with mig?




Another idea was expoxying (JBweld) an allen head bolt to the top of the adapter sleeve (it's hollow at the top) which threads into the stud. This way I can hold it in place with an allen key while tightening the nut down.

LMS suggested knurling the bottom of the stud (sorta like splining it) but not sure if that will help since it's not a tight press fit.

Any ideas/suggestions?


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## mikey (Apr 29, 2019)

I can think of several options, just to throw something out there:

Drill and tap a hole in the side of the compound for a set screw that would bear on a flat milled into the side of the stud.
Use permanent loctite to put a sleeve on the bottom of the stud, then loctite that assembly into the compound. You can get it out with a little heat if you have to. 
Another option is to press the sleeve/stud in place and then lock it it with a roll pin. The hole for the roll pin would be centered on the edge of the large diameter at the base of the stud, such that the hole cuts into both the large diameter and the edge of the hole in the compound. This hole must be drilled all the way through the compound so you can get the pin out but this is how Emco locks their studs on the Compact 8.
Knurl the base of the stud as LMS suggest but also loctite it in.
Make a new stud that will press fit properly into the existing hole in the compound. I would still loctite it in.
I'm sure there are many other options ...


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## stioc (Apr 29, 2019)

@mikey thanks. So far I like the idea of a keyway or a rollpin like you suggested as those would be the simplest/quickest (provided I don't break the 1/16" drill bit in the process) but I'd have to check to see how much room I have on the big diameter of the stud.


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## mikey (Apr 29, 2019)

I would suggest at least a 1/8" diameter roll pin if you go this route. If you do this, be sure to put a spacer/washer/nut over the stud and lock it solidly so the stud cannot move when you drill it.

I'm interested to see what the other 9X guys did.


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## savarin (Apr 29, 2019)

Heres how I did it.








						The 9x20 Mods Thread
					

My 9x20 has a couple of mods including a qctp and 4 bolt clamp for the top/compound slide. I have noticed there is still a fair bit of flex under some conditions, parting being one. The fixing bolt for the qctp is still the original skinny one but with spacers. I will be drilling and tapping the...




					www.hobby-machinist.com
				



At post 12
But after going down the 4 bolt clamp, pitkin doughnut route I eventually made a solid plinth and removed the top slide completely and only replace it for small tapers. I do heaps of single point threading with no problems.
I think that all the flex in the standard top slide assembly is worth removing by the solid plinth.








						Plinth For Qctp On 9 X 20 Lathe
					

In my never ceasing search for more rigidity in my lathe I decided to make a plinth for the qctp. In its normal configuration I can often see the complete top slide assembly flex slightly. (I think I punish my lathe a bit) After seeing Bill G's plinth I felt it was time to go. I forgot to take...




					www.hobby-machinist.com
				



I also removed the detente plunger as I found it annoying and set a paper shim between the tool post and base,
And get rid of that pathetic excuse for a 4 jaw that comes with the lathe you wont believe the difference a real one makes.


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## stioc (Apr 30, 2019)

@savarin thanks for the example. If I'm understanding it correctly looks like you drilled/tapped the stud that came with the AXA toolpost and threaded a screw from the bottom?

What 3/4 jaw chuck are you using now? how much do they run? I know I want the G4003G or the equivalent PM lathe down the road so I'm trying to avoid investing too much into the 9x20. Of course, I still want it to be useful until then


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## stioc (Apr 30, 2019)

OK so I ordered the roll pins from Amazon which should be here on Wed but I believe I've fixed it already haha. As soon as I got home I ran into the garage and started figuring out the next move. Unfortunately the large diameter of the stud was barely 3/32" bigger than the stud and even then it would've required very precise drilling. However I noticed that there was some friction as I pushed the stud in and out of the hole. I cleaned the hole and the stud with brake cleaner and now I could feel even more resistance but not enough to keep it from turning under the load of a wrench. So I decided I was going to create friction everywhere. I put an emery cloth on the surface place and scraped the bottom of the AXA TP, and the top of the compound rest where the TP sits. After that I decided to knurl the bottom of the stud as LMS suggested. The only problem was I couldn't do the knurling on the lathe...or could I?

Folks don't try this at home...but I couldn't come up with a better option






At 120 RPM and using my (now tired) fingers to push the tool into the stud for a good 30 mins I thought I had enough of a knurl to give it a try...and wow to my surprise I couldn't beat it into the hole with a small hammer. I put red loctite on it, grabbed a bigger hammer and a punch and set it into it's place





I was able to tighten the AXA TP fairly well at this point but I didn't want to overdo it until the loctite was dry. But I had my lathe back and I wanted to back up my work by driving an allen head into the hollow center of the stud sleeve. So I chucked up an appropriate sized bolt. Turned it down to about .04" oversized. Knurled it and then pressed it in with red loctite.






It was a very tight fit, I was afraid it might splay the hollow top so I threaded the nut around it...which later had a slight bit friction but not bad.











It's fully seated





A quick test and all seems well. I think the knurled bottom of the stud+red loctite alone should be plenty to keep the stud from spinning...so the hex top was more belts and suspenders. I love it when my hack job plans actually work better than expected 

Thanks to @mikey and Chris from LMS for the knurling suggestions...I never would've thought that knurling actually makes a tighter fit almost like the teeth are raised and you actually gain some diameter.


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## mikey (Apr 30, 2019)

Where there's a will, there's a way! Glad you got it sorted, stioc. I bet that lathe will hog aluminum now!


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## Aukai (Apr 30, 2019)

Congratulations!
Just checking on a safety note for the press picture. Is the press plate that the vice is on a steel plate, or cast iron? They are moving away from cast iron plates now because they shatter, and fly apart under load.


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## savarin (Apr 30, 2019)

stioc said:


> @savarin thanks for the example. If I'm understanding it correctly looks like you drilled/tapped the stud that came with the AXA toolpost and threaded a screw from the bottom?
> 
> What 3/4 jaw chuck are you using now? how much do they run? I know I want the G4003G or the equivalent PM lathe down the road so I'm trying to avoid investing too much into the 9x20. Of course, I still want it to be useful until then



Thats correct, your slide may be different to mine though.
It was just a generic cheap 4 jaw, I had to make a back plate for it.
See here.








						aligning the holes in the back of a chuck.
					

My new 4 jaw chuck has 4 8mm fixing bolts on the back but the holes do not go all the way through so I cannot use a transfer punch. I need to transfer the hole centres on the chuck to the back plate so I can drill them.  1) How can I do this accurately?  My first thought (only one actually) is...




					www.hobby-machinist.com


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## Bob Korves (Apr 30, 2019)

It is a shame that these lathes and tooling for them are kits needing lots of modification work, instead of something you can just turn on and use happily out of the box.


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## stioc (Apr 30, 2019)

mikey said:


> Where there's a will, there's a way! Glad you got it sorted, stioc. I bet that lathe will hog aluminum now!


Thanks Mike. I need to adjust the gibs etc and also sort out my tooling. I feel the cheap tool holders and carbide inserts they came with could be much better because when I see youtube videos of others their tools just seem to cut without effort. Anyone have suggestions for good carbide tool bit holders? preferrably for CCMT (triangle) bits since I purchased a new batch of them.



Aukai said:


> Congratulations!
> Just checking on a safety note for the press picture. Is the press plate that the vice is on a steel plate, or cast iron? They are moving away from cast iron plates now because they shatter, and fly apart under load.


Thanks for mentioning that. I'm aware of the issue and these are indeed the old cast iron plates, I haven't been able to find an inexpensive source for steel ones. They cost as much as a new press from HF. The good thing is that it's a 12T press, most of the issues were with the 20T press. I also usually put a plate on top of them if I'm going to be putting a lot of force on them. This was may be a 1-2T force so I didn't. I've been using this press for various projects for over 6-7 years and no issues but at some point I'll upgrade to one of the newer 20T ones.



savarin said:


> Thats correct, your slide may be different to mine though.
> It was just a generic cheap 4 jaw, I had to make a back plate for it.
> See here.
> 
> ...


Thanks I'll check it out. I've seen a lot of the 'big guys' on YTube etc use a 6-jaw...I wonder if that's the best of both worlds (3 and 4 jaw)?



Bob Korves said:


> It is a shame that these lathes and tooling for them are kits needing lots of modification work, instead of something you can just turn on and use happily out of the box.


Bob, I completely agree! which is why I want a better lathe, leaning towards the 12x size like the G4003G. Although most just end up getting the PM 13x40GT and have great things to say about them. As I get older I lean towards spending the extra money and getting something that does a good job rather than it turning into another project. When I was younger I bought old beat up cars with 'potential' and enjoyed fixing them. Now I'd rather drive new cars that get me to where I want to go day and night without me 'tuning/fixing' them up. However, the flip side of that is since I don't make money off of my lathe/mill etc if I didn't have to tinker with them I won't have too many projects to do with them either lol What type of lathe do you have btw?

I have to say that I'm proud that I have enough tools, stock, supplies that I can start a small project like the one above and get it done without needing to run to the store. I can do the same thing with automotive work, fabrication and even small woodworking/home type of projects.


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## Aukai (Apr 30, 2019)

Check out the places local to you for drop offs/cut offs, I made extra plates for my press out of 1 x 5 plate/bar stock, and cut my own V & round shapes.


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## stioc (Apr 30, 2019)

Aukai said:


> Check out the places local to you for drop offs/cut offs, I made extra plates for my press out of 1 x 5 plate/bar stock, and cut my own V & round shapes.



That's pretty cool, what did you use to cut 1" steel plate?


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## Aukai (Apr 30, 2019)

I have a Jancy Slugger metal blade chop saw, my portable band saw, and an annular cutter. When the bar was too long to carry I cut it with the XP 45 plasma


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## mikey (Apr 30, 2019)

stioc said:


> Thanks Mike. I need to adjust the gibs etc and also sort out my tooling. I feel the cheap tool holders and carbide inserts they came with could be much better because when I see youtube videos of others their tools just seem to cut without effort. Anyone have suggestions for good carbide tool bit holders? preferrably for CCMT (triangle) bits since I purchased a new batch of them.



I think even the cheap tool holders will work. What seems to separate the higher end tool holders from the cheap ones is the fit and finish in the insert pocket. The better ones have tighter tolerances and the screw hole is precisely located. This makes a big difference in how stable and solid the insert is. Still, a cheap tool holder will work for hobby use.

What actually does make a difference is the insert and it pays to use inserts from a known good maker with the right nose radius. I prefer inserts from Seco, Iscar, Kennametal and Korloy. All can be found on ebay.

CCMT is fine for most work. CCGT inserts work best for aluminum; they will also work with most materials but will not last as long because the edge is more fragile due to the huge rake angles they use on these inserts. If you haven't tried them, look for CCGT-AK inserts; these are ground, polished, uncoated and have an aggressive positive rake that works well for aluminum.

Pay close attention to the nose radius of your inserts. For a small machine like yours that must perform well at low speeds and horsepower, it is wise to use a smaller nose radius. For a CCMT/CCGT insert, the smallest nose radius is 0.004". This insert will have a designation like CCMT 22.50 or CCGT 32.50. That zero at the end is the nose radius size.

This smaller nose radius will help you to keep radial cutting forces in check at smaller depths of cut. In general, the minimum depth of cut you can take will be somewhere between 1/2 - 2/3 the nose radius; you have to remember this when doing finishing cuts. If you have a 0.004" nose radius then the smallest depth of cut the insert is likely to make is 0.002" (0.004" off the diameter) without chattering. You may need to slow your feed to take this cut but it should do it. For roughing, anything over the nose radius will work. How deep this is depends on the power and rigidity of your lathe.

You will see all sorts of grades and coatings our there. I know we are supposed to pay attention to this but I usually don't because my machine is limited to 2200 rpm and I haven't found that the coatings make a huge difference for me. Grades do make a difference (I like CM-1 for harder stuff) but, again, not that much for me.

Bottom line: use the tool holder you have but use good inserts from a known good maker. Look for the smallest nose radius they make and look for a CCGT-AK insert for aluminum.

Hope that helps.


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## stioc (Apr 30, 2019)

Thanks, correction, this is what I ordered. Haven't used them yet *TCMT 21.51, 3/32" Thick, 1/64" Radius*






						Cobra Carbide 40927 Solid Carbide Turning Insert, C520 Grade, Uncoated (Bright) Finish, TCMT Style, TCMT 21.51, 3/32" Thick, 1/64" Radius (Pack of 10): Amazon.com: Industrial & Scientific
					

Cobra Carbide 40927 Solid Carbide Turning Insert, C520 Grade, Uncoated (Bright) Finish, TCMT Style, TCMT 21.51, 3/32" Thick, 1/64" Radius (Pack of 10): Amazon.com: Industrial & Scientific



					www.amazon.com


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## mikey (Apr 30, 2019)

The bottom line still applies.


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## Aukai (Apr 30, 2019)

Korloy any good?


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## mikey (Apr 30, 2019)

The Korean Korloy is pretty good. There is also the Chinese "Korloy" that I suspect I have been duped into buying and it seems to work okay, I think. I tend not to use carbide much so I try to buy good stuff from Seco and Iscar and prefer to use those.


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## Aukai (Apr 30, 2019)

Good to know, thank you.


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## hman (Apr 30, 2019)

Stioc - If you find that the tool post still wants to rotate a bit, it may be because the area just around the mounting bolt is slightly domed.  The cure for this is to chuck up the tool post, get out your old 4-way to hold the cutting tool, and cut a shallow relief (maybe .010") around the center hole and out to about ¼" away from the edge of the QCTP.  This will place the friction (between the compound and the QCTP) at maximum radius.


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## stioc (May 1, 2019)

hman said:


> Stioc - If you find that the tool post still wants to rotate a bit, it may be because the area just around the mounting bolt is slightly domed.  The cure for this is to chuck up the tool post, get out your old 4-way to hold the cutting tool, and cut a shallow relief (maybe .010") around the center hole and out to about ¼" away from the edge of the QCTP.  This will place the friction (between the compound and the QCTP) at maximum radius.
> 
> View attachment 293720



Will do, thanks. So far so good though. Mine looks like this.


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## stioc (May 1, 2019)

I finally got a chance to do some turning. Everything tightened down well I set it to 1000 RPM, chucked up a small piece of alum. I first took a .010" cut, then upped it to .020" then I went for it at .054" with the auto feed engaged at .004" feed rate. Wow, even with a well used insert it ate it up and the finish was pretty good too! Not sure I would want to try any deeper though, may be with better inserts.

In any case it's like a new lathe! I want to try steel but don't have any decent low carbon stock on hand.


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## mikey (May 1, 2019)

That's much closer to what you would expect from your lathe, stioc. Have you considered trying an SCLCR tool with an AK insert? I suspect that would perform even better. HSS might be even better yet ... something to think about.


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## stioc (May 2, 2019)

Thanks, I'll look into it. I think I need to educate myself on the types of indexable tools a bit to understand the nomenclature better.


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## mikey (May 2, 2019)

Have a look at this set. For the money, one of the best deals I've seen.


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## stioc (May 2, 2019)

mikey said:


> Have a look at this set. For the money, one of the best deals I've seen.



Thanks! I like it. However, since I already recently purchased three new SCLC boring bars and ten CCMT21.51 inserts I'd like to find three holders i.e. left/right turning and a straight threading holder. Know of any good deals on those?

Also, with the CCMT bits it seems one can only make use out of two sides as opposed to the TCMTs where you can use three sides of them.

Lastly, what makes the CCMT work better than the TCMT inserts on a smaller lathe? comparing the CCMT and TCMT the latter seems bigger in size.

Sorry, too many questions...I know.

EDIT: I'll take this discussion over to the other thread about the 12x36 lathe's insert selection.


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## mikey (May 2, 2019)

Yeah, that other thread is probably the better place for this discussion. However, let me address your question re the CCMT vs TCMT question. There is absolutely nothing wrong with the TCMT inserts. They are common, cheap and easy to find and they work. Heck, I own a set of tools from way back that uses them so I know they work well. And yes, you get three usable tips. 

The key difference between the triangular and diamond inserts is in the geometry of the tool holder. The SCLCX tool holder has a 5 degree clearance angle at the front and top edges. This allows a single tool to both face and turn, whereas you need several tools to do this with a triangular insert. This geometry also allows the end cutting edge of the diamond shaped insert to participate in the cut and this affects the finish that geometry produces. A triangular insert cuts only with one cutting edge so they do not finish as well unless you use a big nose radius. For me, that bigger nose radius requires much deeper finishing cuts or it chatters. A CCMT/CCGT insert produces a better finish with a smaller nose radius and takes a much finer finishing cut.

To summarize, both work but the more modern geometry does it better with fewer tool holders and insert nose radii required. In a hobby shop, a good insert lasts for a long time. The fact that I have only two tips vs three is of no concern to me.


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## stioc (May 2, 2019)

Thanks @mikey I appreciate the info!


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## Toolmaker51 (Jan 8, 2021)

hman said:


> Stioc - If you find that the tool post still wants to rotate a bit, it may be because the area just around the mounting bolt is slightly domed.  The cure for this is to chuck up the tool post, get out your old 4-way to hold the cutting tool, and cut a shallow relief (maybe .010") around the center hole and out to about ¼" away from the edge of the QCTP.  This will place the friction (between the compound and the QCTP) at maximum radius.
> 
> View attachment 293720


Of all remedies, this is the most beneficial, a relief. Cutting a relief establishes a 'land'. Just as it sounds, that becomes  solid mount.
The Grizzly design or tool post are compatible in theory, equivalent to any other lathe or post. The failure was execution of one, maybe both. Post less likely as it is ground. A particular relief depth is not the consideration, sufficient clearance is. Note entrance hole of bolt in compound, chamfer of thread not visible, and small chamfer in post. That alone MAY have been the issue. Tapping 'always' raises a burr. There also could be a wire edge remaining in post, where drill exited, not removed by small chamfer. Could keep post from sitting flat on compound.
There are so _many_ fitments lacking relief cuts, which cost mere pennies during manufacture. 
One more good reason to keep feeler gauges, Dykem and felt-tip pens handy. In 2 distinct colors........

It's time _[again!] _to define what some consider a mere hobby. BS! Anything done as a pastime, which is otherwise alike to industry, differs only as not for profit. In some countries that home shop IS the industry. Even profit not the best measure, we invest without hint of compensation, for what seems to benefit us alone. 
When a country should collapse, who do you think will be up front getting it running? Those jokers sitting in cubicles?


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## savarin (Jan 8, 2021)

I found a brown paper shim under my tool post worked a treat to stop twisting


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## Toolmaker51 (Jan 8, 2021)

2-1/2 explanations. I'll bet the paper was full size the toolpost. 
The main change is certain, different friction characteristic compared with metal to metal. 
A high spot compressed one area, and contact widen.
Like machining a relief, but the center was not high as remedy in answer to earlier post.


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## Tozguy (Jan 9, 2021)

If the bottom of the QCTP is flat and the top of the compound is also, that is how you will get the greatest area of contact and traction. If the compound is not flat, rather than dish out the underside of the QCTP to accommodate the misshapen surface of the compound it is better to fix the problem surface on the compound.
Otherwise by 'relieving' the underside of the QCTP there will be a risk of further deforming the compound mounting surface in use. The QCTP body is by far the more rigid of the two parts and tightening the mounting bolt will only serve to deflect the compound into the 'relief' cut in the QCTP.


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## jwmelvin (Jan 9, 2021)

Two flat surfaces are great when placed together but when clamped with a single bolt, the stress is focused around that bolt. A relief will move the stress outward and result in much better torsional resistance. It also has much better vertical stiffness. The joint with a relief is better in all ways.


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## Tozguy (Jan 9, 2021)

savarin said:


> *Re: 9x20 tool post flex*
> 
> 
> 
> ...





lear133 said:


> but ultimately the compound is the enemy. Makinging a solid platform for the qctp and only using the compound when needed is a better solution on a 9x20. That let me start taking much heavier cuts and part larger diameter steel more successfully.


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## Toolmaker51 (Jan 9, 2021)

Any threaded fastener 'X'  is chosen for it's diameter, thread pitch, and material to deliver and retain administered torque. Torque is not tightness per se, but measurement translated from stretch; planned deformation of the fastener. Pulling a wrench is no guarantee of secure fitting. 
Sought after stretch is affected by many factors; friction of threads and washer faces, bending stress when those faces are not parallel, temperature and thermal differential, condition of surfaces being clamped, sealing requirements [ie gaskets], area to be clamped and more.
Mechanical connections are subject to specific primary/ secondary forces by design.  A pipe flange or carburetor mount is linear, a drive shaft or pump & motor is axial. 
A tool post directs linear downforce into cutting depth [part of centerline importance] and lots into axial, as it directs into feed rate. The distance between tool tip and the post fastener multiply axial load for the post/ bolt/ face combination. 

Simple visual demonstration or real test. Face off two plates of same size at same RPM and feedrate; then one drilled and tapped for a large screw, clearance hole the other but no chamfers. 
Assemble finger tight but securely. Holding one in each hand, twist them in opposite directions. 
Next, mark one with a few strokes of felt-tip and lap just a couple 45° strokes on flat dry abrasive. Observe that the center nearly guaranteed shows less tool & pen marks than perimeter, clearly a raised surface. The 45° strokes and pen illustrate evenness of surfaces. 
Next relieve center of one about 1/2 it's diameter [surface area] and chamfer the parts as is common. Assemble the same as possible manner, and twist. It may still move, but greater effort required. That tiny but same amount of torque was distributed over lesser area = greater load per square inch.

Not to say QC tool posts need a relief, hardly any have them. But .010 or .015 corrected unknown condition of unsatisfactory compound/ toolpost connection. Without a surface grinder, that would be not easily fixed.


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