View Full Version : My 4th axis arrived today... Got some questions... Anyone using theirs?

04-28-2011, 06:01 PM
I was disappointed with a few items:

The wiring provided is very short (3 feet?), I can't mount it on the left side of the table with the provided wiring.
It is provided as a permanent mounted/wired package - you can't unplug it and remove it from the machine without going in to the electrical panel and fishing out the wires every time.
The center looks a little cheap, haven't used it yet, so hopefully it works better than I expect (adjustment of the height is my main concern).
It came with no information about any of the components. Just instructions on how to wire it up to the existing controller. If I want to use it somewhere else, I have to reverse engineer all the info.
There is no home/limit switch included. Will have to home-brew one.

The good:

Mounts vertical or horizontal.
Relatively tight format- I expected it to take up more space. Definite plus.
Backlash appears to be zero. Haven't turned it yet to confirm, just tried to wobble it back and forth by hand.
Stepper looks quite beefy, and since it is geared down (though I don't know how much), it should have tons of torque...

I did call Phil with a few questions, but I have MANY more. If it is on the website, I can't find it anywhere... So, can anyone answer any or all of these for me?

Should I change the oil at some frequency?
[**]With what/where/how?
Can I change/adjust backlash if it wears?
The machine is marketed to the hobbyist market (I think)... Got any pointers on:
[**]How best/easiest to tram (if that is the right word for a 4th axis) the system in to place? Both the table and the center (no faces on the center are ground, are they?)?
[**]Recommended ways to hold parts that are being machined?
Speed ratings to use for CAM programming (rpm max?)? How fast can it rotate?
How about some specs on the table itself:
[**]What is the max torque?
[**]How accurate is the positioning?
[**]Rated backlash?
[**]Taper spec on the center?
[**]Spec on the table mounting (Phil said 12 mm T-Slots - what about the center hole, is it a spec/standard/taper or just a hole?)?
[**]It doesn't come with a limit/home switch... Got any suggestions?

I sent all these questions in an e-mail to Phil as well. I will post up answers as/if I get them.

I have collected the parts I plan to use to make the unit electrically removable. Hope to get around to it this weekend. I scanned in a small figure of Mary that my sister got 35+ years ago as a kid in Oberammergau, Germany (they do a world renowned Passion Play every year), and I plan to make a ~3x size replica for her birthday as my first 4th axis project (original is about 4 inches tall, hand carved)... Also hopefully this weekend...


04-28-2011, 07:04 PM
I went back to the PDF that SWATH posted here: http://www.cnczone.com/forums/mikinimech/118983-anyone_have_mikini_4th_axis-post881143.html#poststop

and got a few answers...

Max RPM suggested is 10
90:1 reduction
300 Watt stepper with 850 in-oz of torque
Repeatability of 28 arc seconds
Sealed for use with flood coolant (good to know!)

It also gives me a few more questions, though...

The center in the PDF:


The one I got:


I sure like the one in the PDF better! It is at a fixed (and assumed correct) height for the table when it is mounted vertical. It has an easy to use brake on the center - I can't even tell if mine has a brake.... Also a pet peeve, the nut to adjust the height of the center is even bigger than everything else on the machine - another wrench that needs to hang out (though I guess it never needs to be adjusted once it is right?)...

This PDF shows it mounted on the left side of the table - I can NOT do this with the items I was provided (the pic does appear to not be electrically hooked up, though, I don't see any wiring coming from the stepper).


Brian L
04-29-2011, 02:09 AM
I have run machines with all sorts of rotary tables, back before they were true 4th axis, just m code operated indexers to full 4th axis. First, don't know if it's really a requirement, but almost always you will see indexers/rotary tables mounted to the right, not the left. This will help with your length of wire issues, and help keep the motor out of the worst of the coolant stream.

I would find a reliable connection type fitting and wire it in. We had larger Amphenol style plugs with o-ring seals and lock rings to pull/hold the connection together. They had caps to replace the plug when you weren't using the indexer.

That center is pretty cheesy in comparison to what was shown, but it can be adjusted to work fine.... we had a similar unit and the adjustability was handy because we had several different indexers and rarely used a center. Quill lock appears to be the large bolt just under the quill, it appears to pinch the casting and lock the quill.

Holding parts usually requires a face plate type of fixture, possibly collets if the center hole is morse taper or 5C, and if you want to get fancy, you can make/buy a small tombstone with multiple vises.... going to be hard to come up with small enough vises, but plates with Mitee Bite clamps could be used. As for indicating it in.... rotationally you will need to pick up a flat on the fixture or part, then just zero the axis out to that. Getting centered over the axis is a bit more difficult... a morse taper test bar stuck in the middle and then indicate center of the protruding part.... if the fourth axis has keyway slots on the bottom you can install it with keys to your t-slots, and it should repeat to center pretty well.... that is if you can get your home switches to repeat....

Same with the tail stock, if it has slots for keys, you can mount it the same way.... makes it easy to be sure it's straight and on center with the indexer.

04-29-2011, 09:31 AM
Thanks for the reply and tips. Both parts have keys for the table T-slots, but they are pretty loose in the slots (1-2 degrees play?). Will likely replace them with a tighter fit option, or mount the whole shebang to a base plate permanently so that I can just indicate in the assembly all at once.

Brian L
04-29-2011, 09:52 AM
Tighter fitting keys or a base plate are both options. Don't forget though, if the slightly loose keys are in the right position, you can just always pull/push the indexer and tailstock to one side of the slot and it will still be straight. They don't necessarily have to be a perfect fit if the two items still line up.... and it will make them much easier to mount/dismount if you aren't fighting a .0005" fit..... and not doing damage to the table slots.

Honestly.... the number of times we used tail socks was pretty limited, but then we did a lot of casting work. The most complicated we did with an indexer was build an intake manifold for big block Chevy's. Decked the bottom surface (what goes over the lifter gallery) and then mounted it on a Has indexer on our Fadal 4020 mill and proceeded to complete every other machined surface on the part in one clamping. I built the fixture plate to hang low, so the weight/position of the manifold was fairly centralized. On the far end away from the indexer we added a cast iron knee with a hole bored to fit a spud on the end of the fixture plate, made a large (6" or so diameter) aluminum piston and sleeve affair to use as a pancake air cylinder and using a spare m-code on the control to activate a solenoid, would clamp/unclamp the end before/after rotation.... worked like a dream.

Here is a picture of the unit we used to make, this was back in the early 90's, don't know who he uses now... but we did all the prototyping, I actually drew the blue prints and spent a week with three engineers from General Motors in my shop getting the whole process and parts approved and given an actual GM part number so they could be ordered through their Marine racing division.


04-29-2011, 01:06 PM
Nice! I told my friend it would have been easier to do this on his 4th:



Custom adapter for a Vortech supercharger to mount on a Ford 351...

He has had this Haas VF3 for years, but only does 3 axis work (actually almost only 2.5D...). I have been trying to push him to do more 3D, and have done a bit of CAM work for him. Slowly but surely I will get him there! By the time he gets there, though, I will be 5-axis on my Mikini!

04-29-2011, 03:27 PM
At "Mcphill" 's direct request, this is being posted in this forum. This is a reply to an email received from this user.

We generally would not post privately sent email, but have had repeated requests by this individual to do so.

Our reply is below

We welcome and encourage feedback, and we're here to help all users. Feel free to be in touch.

- Mikini Mechatronics, LLC

: Received from Mcphill

I apologize if the "hobbyist" remark was off base.

 No problem. Just understand our marketing and documentation is not targeted at this segment of the market, or at new user training. I suspect this is much of the focus point of your commentary and frustration. If it should be, and there's a demand, we're here to respond.

you stated you were developing the 1610LP for the "real machining"
environment about a year ago, and that it was due out "soon" - what happened
to that?

 This is an incorrect assumption (in that one vs the other machine is for “real machining”). The 1610L and LP are designed to make the same parts,(size, precision), at differing rates. One is designed for less optimized cycles (L), and the second to make the same parts faster (LP). Our development cycles for machines is running 3 years, and we are on track.

I do feel greatly privileged to be
able to have bought the machine, and I don't want any of these conversations
to take away from the fact that the machine itself is an excellent piece of

 Thanks for the compliment.

I do have manual machining experience, but no CNC other than a
Fireball V90 I got to prove to myself I could do the CAM and MACH3 work that
would be needed for a "real" machine - I have not had any real stumbles thus
far... That being the case, I feel woefully under-informed on how to
actually care for the hardware you have sent me, using only the
documentation provided as my source for education/information.

 No question. The machine manual is woefully inadequate for education to learn to use a (any) cnc machine, let alone do so effectively. What you describe is learning a profession. We highly recommend taking a formatted course (not a weekend hobby oriented “crash” course), or mentoring under a professional. Not doing so is highly in-advisable. No different than learning to drive a car, fly an aircraft or operate heavy equipment. The user’s manual on an automobile does not teach you to drive. You can teach yourself, but it’ll be bumpy at best, and expensive (time and money) in the long run.

I do feel I am pushing you in a direction that I think will be beneficial to you in the long run, and I apologize if my pushing is seen by you as off-base.

 No problem. We encourage user feedback. More is better.

I also
think that the CNCZone forum provides you the platform to educate "the
masses" about your machines, to solicit feedback, and to grow your
reputation and user base. If you choose not to use it as such, that is your

 Fully agreed that for the “target” audience it seems like a good tool. As discussed we have considered a “hobby” specific machine to address some of these issues with specific features and performance geared to the differing expectations and experience levels. If there’s a demand, we’re all ears and want to gather all feedback to support it, and agree the best place feedback from these types of users is here.

It is my believe that the 'Zone directly contributed to at least
three machine purchases in the recent past, and I hope that SWATH can get is
machine up and running, as right now it does not look like the best
marketing for your machine...

 We’re supporting this user 100% of the way. When the machine is physically labeled 250VAC max, and the schematic says do not exceed 250VAC, It’s not a loose suggestion, it’s the requirement. This particular machine is operating above 250VAC RMS, on power that is surging even above this, and on a ground that has 10V or more of potential. All documented by the user on forums and in direct communication. We’re assisting him to fix this (both machine and facility/installation specific).

You can't recommend anything as far as changing the oil? Hours of running,
calendar time if never used, nothing? I don't even know where to PUT the
oil (I admit, I have not looked at the unit yet, but I should not have to -
it should be in the provided documentation). Same with the backlash
adjustment - this is not a "one off" request, it is a required maintenance
procedure that should be easily available, actually it should be provided
with the unit.

 The rotary table uses GL 5 gear lubrication. You can have it industrially analyzed If you don’t feel qualified to make a determination on quality. Or you can change it as often as you wish. Again, really depends on use. This is the same lubricant used in automotive differentials commonly labeled as “lifetime” for what it’s worth. We could fix a recommendation, but it could lead to users having to change fluid without basis in many cases.

- If you looked at the thread I posted, the center I received is no where
near as "nice" (in my opinion) as the one in the PDF flier - is the one from
the PDF still available? If it is not, why did you switch to the new style
(I will be honest, I think it is because it is cheaper for you...)? Every
center I have used before has a brake on it like the one in the PDF, the one
I received is nothing like any I have used before

 The 2011 rotary kits provide an adjustable tailstock with an exchangeable center. It’s more expensive for us, and offers more capability, but we feel it’s expected at this level of performance. We kept the price the same. More than happy to provide you with a fixed, non exchangeable center if you wish (or I’m sure you may have takers here to trade). They do look prettier with less hardware …

 We ship the 4th axis kits with a hard wire, conduit enclosed sealed fixed fitting. Your photos show this removed. It’s our recommendation to install in this manner as shipped. There are substantial risks to modifying the electrical connections, do so at your own risk. The minimum requirements for the connector in use would be IP67, 80V, 10A, 4 conductors, sealed/safe when removed. A failed connector could be lethal if you dis-respect the other guarding recommendations in the manual – no kidding. We recommend rotary table installation on the right side of the table. If you choose to modify you should do so only with a specific application and understand the limitations of longer cable runs, and again, at your own discretion.

To some of your comments:

Setting up on the table/rotary fixture/center is just like setting up any
other fixture / vise / tool on the XY. Indicate it in.

How do I indicate in the center, when only painted surfaces are available to
me? I need a true ground edge to properly indicate it in - where is that
ground surface (reference attached photo)?

 Indicate to the tool being used as the center, not the tail stock body. This will vary by setup.

Without a brake on the spindle
(or whatever you call it on a center), I don't trust the spindle to be
true... What is the taper on the center? I would rather have a live
center, so I need to know the taper so I can buy a new one. If I were an
experienced machinist I would know the taper by looking at it - I admit I am

 Great learning opportunity as you point out. The assembly is the tailstock. The Center is the tool in the bore. Here are sizes of common MT tapers for reference.

 If you choose to exchange for a 2010 tailstock you’re limited to the dead center provided.

Size Diameter Diameter Length
(small end) (big end)
#0 0.25" 0.37" 2-11/32"
#1 0.37 0.47 2-9/16
#2 0.57 0.70 3-1/8
#3 0.78 0.94 3-7/8

Backlash is adjustable. Happy to walk you through the procedure. You'll
see a black cap with 8 screws. This is the preload. One set of 4 is the
limit, the other set tightens against the limit/screw.

Please send me a documented procedure. If you don't have one, we can talk,
and I will create one (as stated above). Which set of 4 screws is which?

 Happy to send you a quick write-up as a formal document. Set screws are limits, opposite set are adjustments to the limit. 1: Loosen adjustments and limits. 2: Set backlash/preload to desired setting using adjustment screws. 3: Tighten limit screws. 4: Double check tightness of all limit and adjustment screws. 5: Check backlash to ensure setting still as desired. 6 - Done

 This again segways into our previously mentioned consideration of having a hobby specific machine with more user specific fixture / use documentation, more comprehensive tooling packages, included coolant/lube startup kits, Residential Power plug installed at user preference, bigger safety zones (mechanical and electrical), slower feeds/accelerations, pre-calculated feeds/speeds/tools/materials, etc, and resulting lower performance for the same metrics. We’ve even toyed with the idea of adding enough safety systems and limiting performance to the degree that we could make it “crash proof” and offer a crash warranty. None of this will replace training though. Thoughts ?

My ideal response to this discussion would be to have you post all these
answers on the CNCZone forum. My next favored would be an e-mail response,
but I will tell you now that what I would do is post that information to the
forum myself. It would be in your best interest, in my opinion, to "put it
out there" yourself. Lowest desired response (but above no response at
all!) would be discussing it on the phone. What I am asking for are "fixed"
specs and or procedures. If we talk on the phone, I will just have to
transcribe it all to documentation that I can refer back to (and also will
post it on the 'Zone - I bet you see a trend here?). Does none of this
exist in documented form now? I don't understand how every one of your
customers (hobbyist or Fortune 100 company) would not have the exact same
list of questions that I am asking...

 At your wish. We don’t commonly have these questions to answer your question. We don’t have or supply user level fixture/setup/application/use documentation, but more than happy to help users make informed decisions. Again, much of this points to training/experience and target customer bases.

Work Safe

- Mikini Mechatronics, LLC

04-29-2011, 04:07 PM
I did indeed make the request, thank you. I will digest this and get back to you.

04-29-2011, 04:36 PM
Indeed, my problems seem to be very unique and likely directly related to my residential power supply/ground which I have had the power company try and rectify. The machine itself is awesome and Phil has been very helpful as well as patient in helping me trouble shoot despite me not knowing a lot about electricity, my expertise is pretty far removed from this whole arena. Still very glad I went with Mikini although very anxious to use it.

Brian L
04-29-2011, 09:58 PM
Reading the response from Mikini... a few thoughts of my own, take it for what it is worth.

Seems to be some issue as to what to call the machine... hobby or what, professional? I'm sorry, but any machine running open loop stepper drives, with no cognizance of true location and using Mach 3 as a control system is a hobby based machine. Per a thread the other day about the homing switches, you can't even promise accurate homing. I would have to say that accurate homing is a definite requirement for any "professional" machine. I start a machine up in the morning and it better be able to be brought back to a position relative to the locating spud on my fixture, so I can hold .002" true position to the features on the first side, while doing the features on the second side.... that's just a normal expectation of a "professional" machine.

Per other previous threads... a jog pendant that can't be turned to fast, or turned to slow without jumping and loosing steps.... again, not something that would ever be lived with on a "professional" machine. Now is the machine a step above the other current offerings in the $10,000- $15,000 machine choices, maybe, I can't say and leave that to the folks that actually own them.

Regarding manuals.... I haven't seen the Mikini manual, but the machine should have a complete maintenance manual, parts list and at least a basic manual that covers the methods of operations on how/what to do things specific to this type of machine. Things such as what sort of lubricants, what sort of coolants, preventative maintenance, how to set backlash, machine parameters, interface between Mach 3 and the machine itself. For example, you state GL-5 lubricant in the indexer, would that be 80w, 90w, 80-90w, or 85-140w? And how much, and what is the procedure?

I wouldn't expect you to have a complete manual on Mach 3, plenty of other, better avenues to delve into that.... but anything machine specific is a must, and should be clear, well written and understandable.

Actual machining practices should be up to the owner, they take a class, learn from the school of hard knocks, get a mentor, whatever it takes.... CNC machines aren't the "push button solution" to perfect parts.... the operator/owner still has to know machining practices and conventions, speeds and feeds, material selection, tooling and fixture methods.... all of that "stuff" that comes along with being a machinist. I am constantly amazed at the number of guys that expect perfection by being able to draw a part on their CAD system, export it to their CAM system, push a button to code it, not understand a line of g-code.... and then expect the machine to pop out a perfect part!

04-29-2011, 10:32 PM

Regarding manuals.... I haven't seen the Mikini manual, but the machine should have a complete maintenance manual, parts list and at least a basic manual that covers the methods of operations on how/what to do things specific to this type of machine. Things such as what sort of lubricants, what sort of coolants, preventative maintenance, how to set backlash, machine parameters, interface between Mach 3 and the machine itself. For example, you state GL-5 lubricant in the indexer, would that be 80w, 90w, 80-90w, or 85-140w? And how much, and what is the procedure?

This is by far my biggest area of concern/gap with what has been provided...

05-01-2011, 12:46 AM
Hey McPhill,
I will consider trading my tailstock (same as in PDF) with the one you got. If you are interested PM me.