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    Default Optimum MH25V

    Hi guys,

    I have a question about the Optimum MH25V machine. I saw in the catalogue that it is quite new and there is not much info on this machine available online.

    I see it as a very good candidate for CNC conversion (compared to the BF20/G0704), reasons being:
    - twice as heavy
    - AC spindle motor, 1.5kW
    - already belt driven
    - BF30 tooling. some would say expensive, but almost ATC ready
    - wider Y-axis (210mm)
    - Z-axis counterweight as standard

    Having this said, are there CNC conversions available? Does anybody already own this machine? If so, can you please share some opinions?

    I want to purchase this machine and I would like some additional info before I spend my good old $$$.

    Price wise, even if the machine is more expensive then the BF20/G0704, when you start adding the kit cost for new motor, belt conversion, new quick tool change spindle, new spindle bearings, counterweight you end up with the same money (or more). Not to mention the time and effort you put in upgrading.

    Therefore, your thoughts about this machine are most welcome.

    Thank you,
    DLF

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  2. #2
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    Default Re: Optimum MH25V

    So, almost 1 year later, still very little information is available on the web.

    Besides the other CNC conversion thread on this forum there is only 1 other place where I found some decent info about this mill: https://zuendy.de/2017/06/20/optimum...hrungsbericht/

    Anyhow, after Christmas I decided to buy the mill and today it arrived. I still have to clean it and check it with the dial indicator, but so far it looks and feels fantastic. Could not be happier.

    It will be converted to CNC in the next months using Delta 750w AC servos (direct drive) and a SZGH CNC controller. I do not really fancy going the Mach4 route.

    I measured the lead screws. They are 16mm and there is not much clearance around them, so I can not really say if 20mm ballscrews would fit without milling the saddle (on the X and Z). Y would be no problem.

    So far the only difference I noticed compared to the other 25s I saw pictures of is the VFD which now is a Siemens vs. Emerson in older mills. I do not know if this is good or bad since I am not familiar with neither

    Sent from my SM-A520F using Tapatalk



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    Default Re: Optimum MH25V

    Made some progress in the last days.

    Spindle speed was set between 210 - 3850rpm, vs. the advertised 200-4000rpm. Re-configured the VFD so the spindle speed is now 60-4100 RPM. Could go lower then 60rpm since the spindle motor has forced cooling. But I could not go above 4100rpm without the motor's magnetic field slipping (lots of armature noise) while accelerating. Perhaps can be solved by decreasing the acceleration timing in the VFD so the rotor has enough time to catch up.

    The spindle temperature was also checked. After 15 minutes@1500rpm + 15 minutes@4000rpm I measured the following temperatures:
    - spindle motor: 32 deg. C
    - spindle housing TOP: 48 deg. C
    - spindle housing Bottom/spindle bottom ring: 52 deg. C
    - inside spindle taper: 63 deg. C



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    Default Re: Optimum MH25V

    Today I started disassembly. I am a bit disapointed since I found a lot of swarf where I shouldn't have found any. No damage to the slideways, so no harm done.

    I will take pictures and measurements as I progress. Pics I will post, measurements will be used for a Fusion360 model of the machine.

    If anyone is interested in some dimensions or hi-res details please ask and I will post

    Sent from my SM-A520F using Tapatalk



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    Default Re: Optimum MH25V

    The machine is now completely disassembled. I will start cleaning all components and in parallel do the necesary measurements and planning for an initial cnc conversion using the original ACME screws.

    What came as an unpleasant surprise was the column which is not fully enclosed. Instead it has a rather large cutout behind the electrical enclosure. The cutout is part of the casting process, but I am pretty sure it is not helping the machine rigidity

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    Default Re: Optimum MH25V

    Quote Originally Posted by DLF View Post
    The machine is now completely disassembled. I will start cleaning all components and in parallel do the necesary measurements and planning for an initial cnc conversion using the original ACME screws.

    What came as an unpleasant surprise was the column which is not fully enclosed. Instead it has a rather large cutout behind the electrical enclosure. The cutout is part of the casting process, but I am pretty sure it is not helping the machine rigidity

    Sent from my SM-A520F using Tapatalk
    Well as it's a manual mill soon to be a CNC mill I wouldn't be worrying about that.

    When you use it as a manual mill it's under manual control and that means minimal back and forth driving due to the time it takes to reset the slides etc...…..very tedious taking small cuts constantly so you tend to dig the cutter in as deep as it can go and hope it doesn't shake itself to bits.

    Under CNC conditions you can just let it cut away to itself with lighter cuts until the job's done,,,,,you won't be standing over it waiting for a longish X cut to finish so's you can measure the workpiece and then resetting it to do a Y cut etc.

    Just my opinion and I think the real problem you will face is the fact that it has dovetail slides and Acme screws.

    With a machine of this quality???.....unknown quantity......I would have from the outset considered the possibility of reworking the dovetails to fit linear rails.....especially on the Z axis ways, and definitely fitting ball screws.

    What is BF 30 tooling.....Is that an ISO 30 spindle taper?

    I assume from looking that the head casting does the Z axis moves.....IE that it does not have a quil.....your CNC endeavours have a real CNC chance there, but as the head casting is not designed to be unlocked and moving, as in a CNC machine, you will get problems with a loose Z axis slide way when the head is required to be constantly moving.....fitting linear rails here is the answer.
    Ian.



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    Default Re: Optimum MH25V

    Hi Ian,

    Tooling is BT30. In my initial post the BF is a typo.

    The machine will first be converted using the ACME screws similar to the G0704 phase1 conversion.

    After that proper parts will be milled under CNC control. Offcourse ballscrews will be used.

    I am also considering linear rails since the machine can only take 16mm ballscrews (would prefer 20mm) and the factory guideways lubrication channels are just s**t. They provide only half decent lubrication for the Y and Z. None for X. Just poor design.

    But in order to make proper parts I need a CNC machine, therefore the phase1 ACME screws conversion.

    The machine is very nice. But, as with all china products, it needs (a little) more love and care in the beginning. It has much potential for a great CNC conversion. But since there is very little information about it on the web, I decided to share my thoughts and to present the good, the bad and the evil. I trully hope it will help others.



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    Default Re: Optimum MH25V

    Quote Originally Posted by handlewanker View Post
    I assume from looking that the head casting does the Z axis moves.....IE that it does not have a quil.....your CNC endeavours have a real CNC chance there, but as the head casting is not designed to be unlocked and moving, as in a CNC machine, you will get problems with a loose Z axis slide way when the head is required to be constantly moving.....fitting linear rails here is the answer.
    Ian.
    While I understand the linear rail reasoning, I do not really understand the Z axis point.

    The MH25 does not have a quill. As a manual mill the whole head casting moves and one can not make that fine adjustments compared to a machine with quill.

    As for CNC control, all the converted machines (w. or without quill) move the head and majority have dovetails.

    So can you please elaborate why the dovetails would not work in this case?

    BTW, the head has a counterweight. Do not know exact weight, but it is lighter then the head assembly.

    Sent from my SM-A520F using Tapatalk



  9. #9
    ericks
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    Default Re: Optimum MH25V

    I like what you doing, thanks for posting the information. this is something i considered before i started my router build. Looking forward to see your progress



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    Default Re: Optimum MH25V

    Opened the spindle casting. Not much to be seen, except the HTD belt (china, noname) and a few electrical connections: 5V for spindle tacho and the emergency switches wiring.

    Spindle pulley ratio seems to be 1:1

    There are 2 emergency switches: one for protection screen and one for spindle pullstud retainer.

    Sent from my SM-A520F using Tapatalk



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    Default Re: Optimum MH25V

    After more measurments it is certain the Z axis ballnut will not fit without moving the Z axis bearing block a few mm forward.



    This will be done by elongating the 2 screw holes towards the back of the block.



    This will allow the ballscrew to be positioned in the middle of the column-Z axis saddle space and provide enough clearance for the ballnut.

    Also the Z saddle will need new holes for ballnut housing and the column has some high spots which must be taken care of, otherwise the ballnut might not slide freely. There are only 31mm between the column and saddle, so it is a tight fit and I would not shave a few mm from the column/saddle unless it is really necesary.

    So, for this machine there is no posibility of making the CNC conversion without machining the castings a little. Required modifications do not seem to be big, but access to a milling machine during this time is needed.



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    Default Re: Optimum MH25V

    Hi, I quite agree with your game plan up to a point.....softly softly etc etc......one of the guys on another thread, name of AZALIN, has been working on a similar build to yours.....a BF20 I think.... but he went the complete path and constructed a new head from aluminium plates all screwed together to form a box with the linear rail bearing blocks on the back

    This was mainly due to the head casting having a quill and also that he had an ISO30 spindle that he wanted to use.

    Making the new head box in aluminium removed a huge amount of excess weight which is something you don't need for fast pecking cycles.

    I think a build like this, which is a major reconstruction, has to be approached from the aspect of what you want at the end without having to redo most of the work again.

    You could reassemble the mill and use it to make the parts.....like a new head etc.....then do a complete breakdown and rebuild in one hit.

    The actual head build AZALIN did mainly required a lot of drilling and tapping but the end result was quite impressive.

    As far as the linear rails for the Z axis this will move the head away from the column slightly so room for the ball screws will occur then but I think this is not the ideal way to go as you still have the rotating back casting to get rid of.....forward planning needs to be done to achieve a better outcome.

    OK, so some butchery is in the offing and that means no going back, but as a CNC mode is required a biting of the bullet is the way to go...…...you already have the dovetail bottom bearing ways truly machined so fitting linear rails will only require removing the side pointy bit of the dovetail to fit the rails etc.....same for the female part of the dovetails on the X and y axis.

    Removing that part of the dovetail can be done without milling as you could drill a series of 3 mm holes all along the top of the dovetail and then split it off with a cold chisel to form a square corner......then carefully using an angle grinder to dress the edge of the now absent dovetail......nothing fits on that face so it only needs cleaning up.
    Ian.



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    Default Re: Optimum MH25V

    Hi Ian,

    Thank you for your thoughts. I must weigh all the options and proceed.

    I do have limited access at a Bridgeport clone, so the milling part does not scare me.

    But, since this is a hobby, I prefer to do it in baby steps and enjoy the ride. This means tearing down the machine a couple of times will be fun.

    Andrei

    Sent from my SM-A520F using Tapatalk



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    Default Re: Optimum MH25V

    More bad news on the horizon. The X axis gib is badly warped. So warped that when I try to install it, it barely slides in the dovetail. Y and Z are only lightly warped.

    Anyhow, I consider them worthless since they will heavily increase wear on the dovetail.

    I contacted the seller. They were willing to help. Discussion is ongoing. I hope they will replace all 3 gibs. Untill this is solved the assembly is on hold.

    Sent from my SM-A520F using Tapatalk



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    Default Re: Optimum MH25V

    Hi, if that gib is a tapered type then you have no problem because over that length the slight bow in the middle is not going to be an issue for adjusting the slide.

    Anyway. I would be amazed if the gib was straight as an arrow over that length.

    Tapered gibs are one of the best methods for dovetail adjustment...……..been in the trade as a fitter and turner for 60+ years and I've seen, made and fitted many.

    Don't mess with it if you don't have the knowledge of a machine tool fitter as you will do more damage than you can rectify.

    What is most important is that you just reassemble it and adjust it to slide smoothly…...attempting to make it fit better will be beyond your limited skill.
    Ian.



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    Default Re: Optimum MH25V

    Hi Ian,

    The gib is not tapered. It is a parallel gib.

    And that bow is not good because it puts a lot of preload in the dovetail making the adjustment setscrews almost useless.

    The contact points between the gib and dovetail are only at the extremities which will increase wear.

    And because it is warped like this the oil film on the dovetail will be scraped off leaving an almost dry metal surface.

    I can accept that it will not be straight as an arrow. But not like this. The gib should contact the dovetail along it's length. And it should slide in friction free when the setscrews are unthreaded.

    And I do not feel the table sliding smooth in X direction. There is a clear difference between X and Y which feels much better.

    Sent from my SM-A520F using Tapatalk



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    Default Re: Optimum MH25V

    Hi, the photo of the gib was misleading as it didn't show it clearly....that is, nothing to judge it's size by...…..looked like a long tapered one etc hence the comment.

    A short straight or parallel gib needs to be a substantial thickness as opposed to just a thin strip of steel that can be distorted by the pressure of the screws etc.

    I think your only action now will be to approach the supplier and attempt to get another gib or two...…...ten to one they will want to have the old one(s) back and that means someone at their end will just give it a few wacks with a hammer and send it back to you.....gonna be a long night honey.

    I would suggest you attempt to straighten the bow out of it by a few careful wacks with a rubber hammer on a flat surface working along the gib as you go......DO NOT USE A STEEL HAMMER...…….this will only cause the metal to expand and distort more.

    It would appear that the metal used for the gib was cold rolled steel.

    If the gib was surface ground to give a flat finish this would have caused the metal to bow due to the locked in stresses from cold rolling being released......highly unlikely that they annealed the gib before machining.

    You cannot machine cold rolled steel and expect it to not distort…..BTDT.

    A surface grinder will only hold it down and when released from the mag chuck the strip will bow up......even if you grind both sides....it's that difficult to work with...….you're working with a virtual spring.

    I think it could be said that you really got what you paid for.....pay a few dollars more and send the gibs out to someone who can render them flat and true.
    Ian.



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    Default Re: Optimum MH25V

    Tomorrow a tech guy will come to my shop to inspect the machine. I am quite confident they will replace the gibs.

    Anyhow, I will not return the gibs untill I get the new ones and they check out at least ok-ish. And only then, if needed I will send the new ones for retrofiting.

    Sent from my SM-A520F using Tapatalk



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    Default Re: Optimum MH25V

    Well, at least you don't have to send the parts back to China......the fact that you stripped it down means the warranty is void, so best of luck getting any replacements but you might get lucky as they would want to have a satisfied customer at the end of the day.

    Quite frankly running a CNC machine with sloppy dovetails just to make it move easily is not my idea of an ideal situation.
    Ian.



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    Default Re: Optimum MH25V

    Quote Originally Posted by handlewanker View Post
    Well, at least you don't have to send the parts back to China......the fact that you stripped it down means the warranty is void, so best of luck getting any replacements but you might get lucky as they would want to have a satisfied customer at the end of the day.

    Quite frankly running a CNC machine with sloppy dovetails just to make it move easily is not my idea of an ideal situation.
    Ian.
    Void the warranty? On what grounds?

    In Europe the standard warranty time is 2 years for new products. Should one not clean the machine for 2 years? Don't think so. I would say the warranty should be voided if the owner does NOT do the recommended preventive maintainance.

    If the machine has suffered modifications then it's a different story. But mine hasn't.

    Anyhow, the tech guy came to check the machine. He agrees to my observations and the seller will request the manufacturer to remedy the problem. Additionaly he checked the machine and found out that only the column needs a little shimming. But that is normal. Other than that the table and column are in good order.

    Sent from my SM-A520F using Tapatalk



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