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Mhajicek, did you get your TRT70 yet?

implmex

Diamond
Joined
Jun 23, 2002
Location
Vancouver BC Canada
Good morning mhajicek:
I ask because I just had a new neighbour move in right beside my shop in North Vancouver.
He's a watchmaker.
He came to introduce himself...had a wonderful time poking around in my shop and getting the tour, and revealed in the conversation that he's thinking seriously of buying a CM-1 with a TRT70 on it.

Naturally I thought immediately of you.

So if you're willing...can you spare some time for a review again now that you've driven your machine for long enough to reveal all its best stuff and its warts too.
I know you talked about putting a TRT on yours eventually...did that ever happen or is it still in the future plan?

I've been familiarizing myself with the bigger sibling to your machine...a DT-2 with a TRT100 on it that belongs to a customer of mine (the robot guys), and I'm having fun figuring out the best workholding solutions for the tiny TRT100 platter.
I can only imagine the challenge with the even smaller TRT70.

So spill the beans if you're minded to...how good is it, what have you done to actually get a workpiece onto it, how rigid, how accurate...you know, all those things a nosy inquisitive toolbreaker wants to know.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
 
Good morning mhajicek:
Current machine inventory:
2021 CM-1 bought new, 50,000RPM, 36 tools, 5 axis drives, probing.
HA5C-T, bought with the above. I use this frequently. It has a little backlash / hysteresis, of about .0008" across a diameter of about 6". In addition to putting stock in 5C collets, I have a Shars 5C fixture mount, with a Lang Quick Point plate on it. Onto this I mount a four sided dovetail fixture I built, or a Lang Makro-Grip 77. I just ran some jobs for which I do a 3 axis op with the Makro-Grip mounted vertically on the table, and then transfer the vise to the HA5C-T with the part still in it, for angled holes and features around the periphery. Kind of a poor-man's 4+1, and with a much larger swing than the TRT-70, which I needed for these jobs.
TRT-70, bought used over PM. I plugged it in, configured and tested it, and it seems to wok fine. I modified and mounted a Xin Dian vise, as I've shown before. I've quoted a couple jobs that would use this, but they haven't come through, so I don't have any actual experience with which to evaluate its performance.
2017 CM-1 bought a few months ago, 50,000RPM, 20 tools, 3 axis only, probing. The machine was a little abused by its previous owner, and the spindle taper is a little bell-mouthed from running tools to big, and running them too hard, so the machine acts significantly less rigid than the other one. It's still already earned its cost back in only a few months. I've looked into getting the taper reground, but that would be about half the cost of a brand new spindle, and not guaranteed to completely fix it. I think a new spindle would pay for itself fairly quickly by increased productivity.

IMG_20220917_004015.jpg
Xin Dian Modified on TRT70 - Small.jpg
 
So spill the beans if you're minded to...how good is it, what have you done to actually get a workpiece onto it, how rigid, how accurate...you know, all those things a nosy inquisitive toolbreaker wants to know.
Accuracy is great. It'll hold tenths all day every day, even if the temperature swings 20 degrees in the shop. I guess that's the advantage of the tiny work envelope.

Rigidity isn't great. There seems to be a sudden drop in rigidity if I exceed 1/4" cutter diameter, so I think most of the problem is the spindle taper. If they made the same thing in HSK25 I think it could be golden. So I've adapted my cutter selection and programming approaches to compensate for that, and it's a really productive machine.

The only glitch of the "Next Generation" control that I've noticed (knock on wood) is that if I insert or remove a USB drive while its running, it can, on rare occasion, lock up the control.

The absolute worst feature of the machine is the chip handling, or rather the compete lack thereof. I can fill the chip bin with Titanium in a day, or fill the whole machine with plastic in a few hours, and there is no mechanism whatsoever to remove chips. I use a shop vac to suck the chips out. There's no coolant filtration at all as the machine comes, just some baffles that don't do anything, so I've jury-rigged some filtration. I'm thinking of designing a better chip pan and filter system, and having SendCutSend make it.
 
If you don't mind me asking a complete n00b question: what keeps that faceplate screwed onto the 5C nose? I've seen some Hardinge stuff with grub screws but, I'm not a fan of doing that into what appears to be a smooth surface. I've been running on the assumption that any torque on the HA5C needs to be taken by the collet and pin.
 
Hi mhajicek:
Thanks for responding with that update.
It looks like you're steadily expanding and your business is growing nicely...congratulations.

I'm rooting for your success, and as you know I've been following your adventures with the CM-1 with great interest as I've been tempted more than once to pull the trigger on one to complement the Minimill I have, and to let me get rid of the obsolete Defiance.

I'm interested to see that you were actually able to crowd a self centering vise onto that TRT70...it looks awfully big sitting there but if it works, all is good.
I'm also a bit surprised that it can handle the weight...I thought the load limit on the TRT70 was some ridiculously small number.

I was toying with the idea of a titanium alloy dovetail fixture for the TRT100 for that reason, and because I figured that if you just always make the dovetails in the stock the same size you don't need a very big clamping range.
I was just going to wire cut a lump and put a spring slot into it for the moving jaw and a honkin' big socket head cap screw to squeeze the dovetail onto the stock.
Something like this:
TRT100 w dove fixture.JPG

I use that system on the wire EDM and it works brilliantly in that application.
Here it is close up so you can see how it's made:
dove fixture.JPG
This has a 1" 30 deg dovetail so I can buy standard cutters for milling the stock, not some weirdass shit I have to pay extra for.

One of the nice things about it is I can sneak up the cutters and toolholders really close to the jaw surface when the TRT is laid over at 90 degrees...something that obviously cannot be done with a vise.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
 
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If you don't mind me asking a complete n00b question: what keeps that faceplate screwed onto the 5C nose? I've seen some Hardinge stuff with grub screws but, I'm not a fan of doing that into what appears to be a smooth surface. I've been running on the assumption that any torque on the HA5C needs to be taken by the collet and pin.
The Lang plate is pinned and bolted to one of these:

 
I'm interested to see that you were actually able to crowd a self centering vise onto that TRT70...it looks awfully big sitting there but if it works, all is good.
I'm also a bit surprised that it can handle the weight...I thought the load limit on the TRT70 was some ridiculously small number.

It is a ridiculously small number. Three pounds. Trimming off the bottom of the vise and lightweighting it helped a bunch.

I was toying with the idea of a titanium alloy dovetail fixture for the TRT100 for that reason, and because I figured that if you just always make the dovetails in the stock the same size you don't need a very big clamping range.
I was just going to wire cut a lump and put a spring slot into it for the moving jaw and a honkin' big socket head cap screw to squeeze the dovetail onto the stock.
Something like this:
View attachment 403794

I use that system on the wire EDM and it works brilliantly in that application.

One of the nice things about it is I can sneak up the cutters and toolholders really close to the jaw surface when the TRT is laid over at 90 degrees...something that obviously cannot be done with a vise.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
Yup, that's another good idea. The guy I bought it from included a mounting adaptor for a 5th Axis dovetail fixture D05125, so I bought one of those.
 
Hi again mhajicek:
If this idea works well, are you interested in having me run one off for you too?
The titanium is not that expensive and I'll happily wire cut the features in for you for free, just to help out a fellow PM guy.
Let me know...I'm likely to build this thing in the next week or so, and if I've got the rotary set up on the wire anyway, it's no great hardship to run two instead of just one.

I can even make it a custom size for you if you shoot me a model.
Looks like your platter size is just under 2.5"
I think I even have titanium Ti6Al4V barstock in that size.
Mine for the TRT100 is going to be 3" diameter so I can get the mounting screws in.
I'd plan on just doing the wire work...you obviously can put in the holes just as well as I can but the curvy spring slot will likely have you stumped.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
 
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Hi again mhajicek:
If this idea works well, are you interested in having me run one off for you too?
Hmm. Tempting, but between the vise and the 5th Axis dovetail, I don't know what other size I'd need? Maybe something smaller, but I'd have to wait for a job to come up to know how small.

I think something that could hold 1/4" or 6mm wide stock might be handy.
 
Hi mhajicek:
Thanks for responding with that update.
It looks like you're steadily expanding and your business is growing nicely...congratulations.

I'm rooting for your success, and as you know I've been following your adventures with the CM-1 with great interest as I've been tempted more than once to pull the trigger on one to complement the Minimill I have, and to let me get rid of the obsolete Defiance.

I'm interested to see that you were actually able to crowd a self centering vise onto that TRT70...it looks awfully big sitting there but if it works, all is good.
I'm also a bit surprised that it can handle the weight...I thought the load limit on the TRT70 was some ridiculously small number.

I was toying with the idea of a titanium alloy dovetail fixture for the TRT100 for that reason, and because I figured that if you just always make the dovetails in the stock the same size you don't need a very big clamping range.
I was just going to wire cut a lump and put a spring slot into it for the moving jaw and a honkin' big socket head cap screw to squeeze the dovetail onto the stock.
Something like this:
View attachment 403794

I use that system on the wire EDM and it works brilliantly in that application.
Here it is close up so you can see how it's made:
View attachment 403795
This has a 1" 30 deg dovetail so I can buy standard cutters for milling the stock, not some weirdass shit I have to pay extra for.

One of the nice things about it is I can sneak up the cutters and toolholders really close to the jaw surface when the TRT is laid over at 90 degrees...something that obviously cannot be done with a vise.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

I wonder if having the full length dovetail as the flexture without a solid top bed would be unstable in cut?

It seems most dovetail grippers have a solid body the part is pulled down onto. The sliding clamp creating a side/downforce to pull the part against the solid bed of the top dovetail
Giving a firm/fixed z height and using the opposing dovetail as a datum x/y
Many also use a pin to prevent sliding through the dovetale under load.

Examples


 
Hi Stirling:
You make good points, and of course, dealing with the second one is easy...I can just put a pin in too.
If I do, I'll make it like the sliding latch on a garden gate, so it can be moved out of the way without having to take it out and potentially losing it.

With regard to the first point...a separate piece for the clamp versus a single piece with a flexure.
IMO both operate the same way...they pivot, collapsing the dovetail a tiny bit, and the dovetail angle is what provides the down force to lock the workpiece firmly onto the platform that will constrain it.
Obviously as the angle of the dovetail increases, the down force vector gets bigger, so the argument is for some weird 45 degree dovetail.
The downforce becomes the same as the clamping force, but the practical reality is that a 30 degree per side dovetail works just as well as a 45 degree per side dovetail, and the claim that one is better than the other is kinda bullshit in my opinion.
It is endorsed by the OEM's so they can sell you an expensive "special" cutter with expensive special inserts to go in it.
Whether the platform is on the bottom of the female dovetail of the fixture or the two top rails is immaterial...it will find the one it hits first and that will keep the part from moving any further...so if your dovetail on the fixture is 0.100" tall, and you make the dove on your stock 0.075" deep it will hit on the rails, but if you make it 0.150" deep it will hit on the floor.
With a flexure dovetail block, my personal practice is the make the dovetail on the stock a twitch taller, so I hit hard on the floor, not on the rails.
That's because the clamp side of my rails is moving, and my clamp is full width, unlike a block with a separate piece for the clamp that moves independently of the rails

Other things to note...as you make the dovetail on the stock smaller and smaller, the clamp becomes less and less effective, mostly because the taper angles no longer match very well on the clamp side...this is true for both styles of dovetail fixture, but theoretically not true for a self centering vise since the clamps do not pivot but slide.
However, again the practical reality is that the vise body bends and the jaws rock as you clamp them, so the main advantage of the vise is that you don't have to be very accurate with the dovetail size and it will still work well.

Dovetail blocks clamp with about the same holding force as the vise does, but dovetail blocks have two big advantages.
!) they are more repeatable because the work is pushed against a solid corner that does not move...this helps if you take the part out and then want to put it back
2) They take up a lot less room so it's way easier to sneak a cutter up close to the bottom of the workpiece when the platter is pivoted to 90 degrees with the A or B axis

Their big disadvantage is you have to get the dovetails on your stock pretty accurate...too big and the stock won't go in... too small and it doesn't clamp worth a crap, and the range is small: +0/-.002" or thereabouts for a 1" wide dovetail 0.075" deep.

So you can still nibble out the dovetail on a manual mill but you have to take care with it, so rolls and a mike and a CAD sketch and all sorts of other minor nuisances.
With a self centering vise, you can just bomb along and if it looks good, it's good.

On my wire EDM, I just wire the dovetails, so I don't even think about it: I can get them consistent within a tenth or two, and this is on the end of a titanium bar 2.5" diameter and a foot long.

So ultimately, if you understand how these things work in detail, you can pick your poison and both will be equally effective.
I favour the dovetail blocks because the platters on the two smallest TRT units are so tiny, so a self centering vise on one looks like an elephant on a bicycle.
I favour the flexure because it's dirt simple to make.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
 
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Out of curiosity, what do you think of those Xin Dian vices?
I think they're excellent for the price. I have a Lang Makro-Grip 77, which is great, but it was about $1k. The Xin Dian's are $60 each, so you can consider them disposable if you want, and modify them to suit your purpose without worry. Even so, they're made pretty well, with a very close fit.
 
I'm curious if you ever considered a 2-jaw chuck for the HA5C. I stole the attached pics from an ebay auction. This is the direction I went for doing the function of a self-centering vise. The idea is to make soft jaws as needed, at whatever width necessary. It could include as much overhang and support against the face of the chuck as needed for the fixture. Haven't used it yet but that's the cunning plan.
 

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Hi Donkey Hotey:
The problem with a 2 jaw chuck is the same as the problem with a self centering vise...the size of the chuck body makes it hard to sneak a cutter in super close to the top face of the chuck, so if you need to mill close to the bottom of the part it can get tricky to sneak your cutters in there, and a common workaround is to just hang the part out further from the jaws.
On piddly little machines like I have, that extra part stickout from the chuck face gets problematic really quickly because these little machines don't handle cantilever forces very well.
I make freaky sex toys (don't ask) so I drill titanium, which needs a good bit of poop to keep the drill cutting...hanging out your part any distance risks overpowering the brake on the rotary or doing other bad things.

Not to say it can't be made to work, but it's always a concern at least for me it is.

In every other respect, using a 2 jaw lathe chuck is just like using a self centering vise...it should work brilliantly.
Being able to bolt on soft jaws and shape them as needed is always nice, sometimes so is the ability to switch between lathe and mill.
It's a perfectly viable plan.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
 
Sorry Marcus, I was more asking @mhajicek since he has the 5C indexer but, you brought up good points. It's different than what you're currently holding.

Since this thread got me wondering (and off my procrastinating butt), I just installed the 2-jaw for the first time. It's so close to the HRT210 that when it snugs up, the back just kisses the mounting plate. It needs a skim cut to the back of a literaly brand new Hardinge chuck :eek: (was just wiping the cosmolene off of it). It's a nice size though. Reading through the HA5C manual, the spec is to tighten anything on the threaded nose to 70 ft/lbs. I guess that's enough torque to resist something at 1-2" radius.
 
Sorry Marcus, I was more asking @mhajicek since he has the 5C indexer but, you brought up good points. It's different than what you're currently holding.

Since this thread got me wondering (and off my procrastinating butt), I just installed the 2-jaw for the first time. It's so close to the HRT210 that when it snugs up, the back just kisses the mounting plate. It needs a skim cut to the back of a literaly brand new Hardinge chuck :eek: (was just wiping the cosmolene off of it). It's a nice size though. Reading through the HA5C manual, the spec is to tighten anything on the threaded nose to 70 ft/lbs. I guess that's enough torque to resist something at 1-2" radius.
Might be nice to have a four jaw with swappable jaws. Then you can grip from all four sides, or take two opposing jaws off as preferred. But chuck bodies are generally round, which means you've got obstruction all the way around for tools running close to the body; a self centering vise usually allows better clearance one way than the other, so you can choose the orientation of your part to suit your features.
 








 
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