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Thread: Itech 6090 ground up rebuild and dial-in

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    Default Itech 6090 ground up rebuild and dial-in

    I have owned a 6090 router for about 3 years, which I use for various hobbies and household stuff.

    From the outset, I will say that this is a lot of machine for what it cost - barely more than the cost of the major components - and has performed really well, cutting everything from slabs of foam, to plywood cabinetry, milling plate aluminium, fine engraving and PCB milling.

    But, there have been various electronic and configuration issues that I have gradually sorted out and I got to wondering how precisely it had been put together mechanically.

    I found a great [link: https://youtu.be/4HWuhbhySpw]series on YouTube[/link] covering the process of dialling in a ‘proper’ CNC mill and decided to adapt the process to my own router.

    As this process progresses, I will try to keep you up to date and share what I learn.

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    Attached Thumbnails Attached Thumbnails Itech 6090 ground up rebuild and dial-in-6bb71fca-f264-4244-8e76-238ae90be61e-jpg  


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    Default Re: Itech 6090 ground up rebuild and dial-in

    “What on Earth possessed you to pull it apart?”

    This was a fair question, given it was working fine after all.

    My shed visitor shook his head at the state of total disassembly and the impressive heft of the components I was attempting to wrangle.

    Well there are several reasons: (1) I have always had a penchant for pulling things to bits (2) I had a reasonable suspicion that it the machine wasn’t set up quite right (3) I am a bit of a perfectionist and (4) I had already gotten excited and invested in a range of measuring equipment which I then needed to justify.

    Aside: It is the mark of a ‘serious hobby’ when you start investing in tools for the benefit of improving your other tools!

    Having watched the YouTube series linked in my first post, I started assembling the following kit:
    - machinists level, 0.002” in 10” precision
    - 500mm precision straight edge (1m would have been handy)
    - dial test indicator
    - precision squares, for the x/y and z axes

    I already had a dial gauge / magnetic base and made a diy tram attachment from T-slot extrusion.

    I started with Tram (squareness of the spindle axis to the bed) which was substantially out. This is evident in the banding I get when milling flat surfaces.

    The video series, however, implored me to start with levelling and do the tram last.

    To get proper access to the Y rails, I needed to remove the cable chain gear, then the water tray / flume. It became apparent pretty quickly that the rails were far from straight and level, with a decent dip towards each end.

    One thing led to another ...



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    Default Re: Itech 6090 ground up rebuild and dial-in

    Sorry, it has been a while! The great CNC dial in is complete but I will try to catch you up on the story.

    **

    Itech 6090 ground up rebuild and dial-in-img_2466-jpg

    Shoving some bits of shim between the Y and the stop ridge and checking with the level, showed things were significantly out, we are talking millimetres at the ends.

    Itech 6090 ground up rebuild and dial-in-img_2469-jpg

    This led to a total strip down, to get to the bottom of the problem.

    Itech 6090 ground up rebuild and dial-in-img_2467-jpg

    Note, I have / had no way of really checking how parallel the Y rails are in the lateral direction (i.e. from left to right) but I could check overall straightness by running the dial test gauge along the straight edge. There didn't seem to be a big issue that way.



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    Default Re: Itech 6090 ground up rebuild and dial-in

    Whilst I pondered what to do about the Y rails, I turned my attention to the other bits.

    Such is the joy of Chinese made machinery, I discovered a few small horrors as I dug deeper.

    Itech 6090 ground up rebuild and dial-in-img_2470-jpg

    This is the X axis plate. You are looking at one of the tapped holes where the Z axis attaches. Except, part of the tap is still in it! Oh well 3 out of 4 ain't bad.

    Itech 6090 ground up rebuild and dial-in-img_2471-jpg

    Finally got the bastard out.

    Itech 6090 ground up rebuild and dial-in-img_2473-jpg

    Uh oh. Another one, this time one of the Z axis rail bolts. This one came out with a little more finesse! I drilled 3 small holes along the flutes of the tap and eased it out.

    Itech 6090 ground up rebuild and dial-in-img_2474-jpg



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    Default Re: Itech 6090 ground up rebuild and dial-in

    Whilst the blue paint on the water tray and main brackets was OK, the white paint was pretty poor. Some of it started to dissolve when I cleaned parts with Brake Cleaner and I suspect it is water based paint. I decided to strip it all back whilst the machine was apart.

    Itech 6090 ground up rebuild and dial-in-img_2475-jpg

    Here they are, stripped and ready for re-painting. Note the pressed-in plug where the broken tap had been. (Although I pressed a piece in pretty hard with loctite, I am not sure if this held super well .. )

    Itech 6090 ground up rebuild and dial-in-img-2484-jpg

    Cleaned, masked and painted (automotive acrylic spray cans)



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    Default Re: Itech 6090 ground up rebuild and dial-in

    Ad break - here are a few of the tools I used in this process:

    Itech 6090 ground up rebuild and dial-in-img_2572-jpg

    From top left:
    - V blocks, for supporting the Z lead screw whilst I re-ground the end
    - Machinists level, 0.002" in 10", for levelling the X and Y rails and reference surface for tramming
    - 5-25Nm !/4" torque wrench, for torquing all critical machine screws including rail mounts, cars, axis mounts, spindle mounts etc
    - Machinists vice, just the right size for clamping the Y rails to the frame whilst drilling
    - Large square for squaring X to Y; small square with flange for squaring Z to X and Y
    - Dial test indicator, for checking rail straightness and parallel(ness)
    - Home made tram adaptor, for use with ...
    - Dial gauge, for measuring tram as well as straightness in X against a reference surface
    - 0-25mm micrometer, for measuring the thickness of shims
    - Feeler gauges, for measuring the gaps that needed to be shimmed

    Also used, not shown:
    - Transfer punches, for centre marking the new mounting holes for the Y rail
    - Reference surface, for measuring X straightness and tram



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    Default Re: Itech 6090 ground up rebuild and dial-in

    Now to get serious! Setting up the Z axis.

    I started with one rail, testing for straightness against the straight edge with the dial test indicator sitting on a car.

    I used various bits of shim, clamping against the stop and tightening the bolts along the way, until I got everything within 0.02mm along the length.

    I then added the second rail and measured it against the first one.



    Finally, all together and ready.

    Itech 6090 ground up rebuild and dial-in-img-2488-jpg



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    Default Re: Itech 6090 ground up rebuild and dial-in

    Back to the Y axis ..

    I figured that the rails were too far off level to adjust properly with the existing mounting holes. Apart from each rail being bent at the ends, there was a significant twist between the two rails, measured by levelling the while bed to one rail then measuring the other.

    By swapping the rails left for right, the mounting holes were in different locations and I could re-drill from scratch. I set up the swapped rails as level as possible with shims and clamps, then used a transfer punch to mark the centre of each new hole.

    Itech 6090 ground up rebuild and dial-in-img-2493-jpg

    Drilling was a pretty awkward affair. The bare frame weighs maybe 30-40 kg? On close inspection it looks like it was cast by digging a hole in the ground and pouring metal in, but you can't say it's not solid.

    Using a variety of blocks, straps, levels and clamps I slowly worked along each side. The actual mounting holes in the track are about 4.5mm which gives a little wriggle room with the standard M4 screws. Despite all my best efforts with transfer punches a couple of holes ended up off centre. I got around this by heli-coiling them to M3 and using a smaller screw.

    Last edited by loska; 12-29-2018 at 03:12 AM. Reason: Fix image orientation


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    Default Re: Itech 6090 ground up rebuild and dial-in

    Back to the X axis - I followed the same procedure as the Z axis; setting one rail against the straight edge then the second rail against the first. With much shimming, I got the deviation down below 0.025mm across the length.

    I then attached the Z axis plate to the cars and when I torqued the car bolts, I found that the rails started to bind.

    On closer inspection, the planar alignment between the two rails was out .. a *long* way out! Look for the air between the straight edge and the right hand car.

    Itech 6090 ground up rebuild and dial-in-img_2515-jpg

    Now the target error in vertical levels for these types of rails (PMI MSA series linear rails) is in the realm of 100uM.

    No worries, a 0.6mm shim between one set of cars and the Z axis plate got things moving again! I can only imagine that everything was set up pretty loose for it to run at all, originally.

    Itech 6090 ground up rebuild and dial-in-img_2516-jpg

    Last edited by loska; 12-29-2018 at 06:53 AM.


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    Default Re: Itech 6090 ground up rebuild and dial-in

    Now things are getting back together.

    Y rails mounted and levelled, X brackets in place, ...

    Itech 6090 ground up rebuild and dial-in-img_2517-jpg

    Re-assembling the X axis, chocks and straps to hold it all in place, cheap level for sanity checking!

    Itech 6090 ground up rebuild and dial-in-img_2522-jpg

    Last edited by loska; 12-29-2018 at 06:06 AM.


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    Default Re: Itech 6090 ground up rebuild and dial-in

    Now to level and square the axes. I temporarily placed a reference surface (thanks to father-in-law for the loan), shimming to level. Note that the Y axis rails are all still levelled at this point and nothing is to be moved! (The machine sits on a trolley on casters, casters are locked in one spot in the middle of the shed.)

    This allows me to check the level across X; there is quite a lot of room to adjust the locations of the X axis against the main brackets as well as the positions of the cars.

    Itech 6090 ground up rebuild and dial-in-img_2542-jpg

    Also in Z against Y, using the small 50mm square, temporarily super-glued to the cast iron reference surface.

    Itech 6090 ground up rebuild and dial-in-img_2544-jpg

    Now the Z axis ended up a *long* way out of square, see here the shim - more of a brick really - something in the order of 2mm at the top to get it vertical. This of course had a pretty impact on the tram as well (that is, how perpendicular the spindle is to the bed).

    Itech 6090 ground up rebuild and dial-in-img_2545-jpg

    Then, checking for squareness of Z against X, adjusted by rotating the Z axis against the X axis plate:

    Itech 6090 ground up rebuild and dial-in-img_2546-jpg

    .. And another way to check, for sanity and ease of adjustment:

    Itech 6090 ground up rebuild and dial-in-img_2547-jpg

    Edit: Forgot to mention, I also squared X against Y using the larger square. This is adjusted where the main Y brackets are bolted to the large cross-beam underneath.

    Last edited by loska; 12-29-2018 at 06:18 AM.


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    Default Re: Itech 6090 ground up rebuild and dial-in

    Finally, back to where it all started, tram.

    This is tested by rotating a dial gauge in the spindle against the reference surface and is adjusted in two axis by shimming and rotating the spindle mount against the Z axis plate.

    Itech 6090 ground up rebuild and dial-in-img_2548-jpg

    Brag video:





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    Default Re: Itech 6090 ground up rebuild and dial-in

    Now to re-install the Y axis lead screw. The end that is driven by the stepper motor looks like it has been free-hand ground with a bench, or worse, angle grinder. We are talking 0.5mm off round! I can only imagine they didn't have the right drive adaptor so fudged it into size. This obviously caused a fair bit of whip around.

    Not owning a suitable lathe, I improvised a means of truing it. Lead screw in V-blocks clamped to the bed of the machine; Dremel grinder bit in the spindle, worked it back and forth and around until it resembled something round and true.

    Itech 6090 ground up rebuild and dial-in-img_2556-jpg

    Not beautiful, but workable ...

    Itech 6090 ground up rebuild and dial-in-img_2554-jpg

    .. with a suitable bit of, you guessed it, shim!

    Itech 6090 ground up rebuild and dial-in-img_2555-jpg

    Last edited by loska; 12-29-2018 at 06:22 AM.


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    Default Re: Itech 6090 ground up rebuild and dial-in

    Finally, to re-install the Y axis lead screw. Using the machine level, I levelled the screw along its length:

    Itech 6090 ground up rebuild and dial-in-img_2560-jpg

    Shimming under the ball nut block, and re-drilling the mount points for the stepper motor and the idler bearing at the other end. Running the axis back and forward along its length allowed the sideways alignment to be checked.

    Itech 6090 ground up rebuild and dial-in-img_2561-jpg



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    Default Re: Itech 6090 ground up rebuild and dial-in

    Tray back on, followed by the T-slot bed, all bedded in Sikaflex to dampen vibration and seal the screws. The tray is designed to accommodate flood cooling which I have never actually used (I use mist cooling for cutting soft metals) but I may as well seal it in case.

    Prior to this I bogged up some depressed parts of the frame where the casting was under-filled, using polyester filler, then filed it back to level.

    Itech 6090 ground up rebuild and dial-in-img_2570-jpg

    All back together, time to plane the foam bed liner back to true flat!

    Itech 6090 ground up rebuild and dial-in-img_2571-jpg



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    Default Re: Itech 6090 ground up rebuild and dial-in

    Conclusion:

    After all, the precision achieved was:
    < 0.05mm along the Y axis
    < 0.025mm along the X axis
    < 0.02mm along the Z axis
    < 0.02mm in 100mm X-Y squareness
    < 0.02mm in 50mm X-Z squareness
    < 0.02mm in 50mm Y-Z squareness
    < 0.03mm in 90mm tram

    On reflection, the biggest improvement was probably from Z axis squareness (which was a long way out) combined with fixing the tram. This means much smoother finish without any banding, more accurately sized parts and probably less stress on tools. X/Y squareness is also important for accurate parts.

    As for flatness / straightness of the X and Y axes, given that material is clamped to the bed and probably has some flex (and the bed is planed parallel with the axes) arguably this would have less impact on overall performance. But it is nice to know everything is set up right!

    The machine is running really nicely now; for example doing very fine PCB engraving work with < 0.01mm deviation in cut depth.

    Even though the build quality out of the factory leaves a little to be desired, the materials are good enough (and the important stuff like rails and ball screws are excellent) to make a great machine for a small price.



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