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  1. #1
    Like a lot of folks here I have wanted to get into CNC for quite a while .
    My workshop is not large and some my machines are old “friends” . I did not really have space for a dedicated CNC lump and much of the attraction was in the process of the DIY build anyway. A learning process which was to become an project in itself.
    I did have a look at converting my old Deckel FP1 toolroom mill but It did not seem an easy candidate and I felt it would have been tantamount to butchering a vintage vehicle .

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    I explored lots of other options and came to the conclusion that one real possibility was to plant an X/Y table onto the machines own universal table .
    This compound table from Axminster tools looked like a pretty good candidate . https://www.axminstertools.com/axmin...d-table-400385 It was reasonably priced (for a tight northern pocket ) and if things did not work out then not too much was wasted. Things got even better though because I found one on Ebay which was new, albeit with some transit damage, and I won it for the princely sum of £40 with a small carriage charge . When I planted it on the table of my mill it fitted easily with still about 200 mm of headroom , (and all the machines own feeds, and traverses still untouched and available if needed)

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ID:	28291 this Chinese compound table fitted easily with ample headroom to spare

    The idea of a Compound CNC table as a removable “accessory “ was appealing as it was light enough to lift off the table and put aside, on the same trolley as my PC and wheel it away into the corner.
    So the project started .
    Last edited by John11668; 16-06-2020 at 04:27 PM.

  2. #2
    I looked at those Axminster xy tables a long time ago when planning my drill press upgrade. In the spec they said it was not a precision table and was only for general xy movement. I also tried one out in the shop and also wasn’t sure about it.

    I also looked at a few of those more expensive red and green ones but wasn’t convinced about the quality from the few videos I looked at. Also travel was quite limited especially Y. So I will be making my own but it depends what you are going for.

    Also looked at spare xy tables for ArcEuro milling machines but they had limited travel and the price was going up.

    I would be interested to know if the ways are tight and straight on yours and if you have swept them with a DTI to say how good they are and if they are close to 90 degrees.
    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

  3. #3
    Am not quite in a position to give you an answer on that Router but I will check and come back to you.
    At the moment I am fitting a new BoB with spindle control which has turned out to be a bit more complex than just a swop .
    When i get all the axes running again I will clock the traverses and let you know.

  4. #4
    I dismantled the table and put aside the old leadscrews, which I have to say were pretty awful.
    I was not really concerned , as by this time I had already decided to replace with ball screws anyway. I settled on a set like these. https://www.ebay.co.uk/itm/Ball-Scre...D09nBYWd-BzNAQ It was a risk but the british prices were so much higher and my guess was that UK suppliers were probably buying from here anyway. And even if they were not of the highest quality they would still be a massive improvement on my rough old table. I also knew it was likely that I would need to shorten them so I did not want to take risks with expensive kit. Delivery only took a couple of weeks and in the meantime I had work to do on the table castings.

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ID:	28300 This ballnut mounting plate was easily fitted to the face of the saddle

    From what I could see the dovetail slides were reasonably parallel to the front and back edges of the table, albeit that the machining was typical far eastern standard, but it would do for the agricultural job I was planning . With the table inverted on my mill and clocked to the back dovetail slide, the front and back edges of the table (and the other dovetail) were all parallel within a couple of thou. My thinking was that even if they weren’t true then as long as I could tighten the gibs to take out excessive slap, then it would do for me. I was pleasantly surprised though.
    I did however run a big end mill over the end faces to ensure squareness with the slides and to give decent square seat for the eventual fit of end bearings.
    I went on to do similar with the cross slide and base . I left milling of the seats for bearings until I had all the kit in hand in order to formulate a plan for mountings here. I ordered the remainder of my kit, bearings fixed and floating, flex couplings , motors and drivers, along wth PSU and breakout board, from Zapp automation.
    With hindsight it might have been cheaper to buy the ballscrews , bearings, couplings etc as a set .
    It may depend on the sizes , and whatever deals are going at the time https://www.ebay.co.uk/itm/Antibackl...harwYhBTXLHl6g
    The arrangement of the ball screws and bearings turned out to be very simple and very much in a similar style to the original screws and mounts , and I was even able to recycle the old bracket on the table end . My first attempt at mounting the x motor did not take into account the endfloat in the motor due to spring thrust washers. When first powered up with a cordless drill there was significant back and forward shift. Plan b involved a steel block mounted to the end of the table to give a seat for a fixed bearing and also to give a fixing for the motor mounting brackets.

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    Please remember that this was always going to an agricultural exercise, a first attempt which might then lead me on to something more sophisticated , so the design is in keeping with that . I was however quite pleased with it when I eventually got it running and wonder how it compares with the typical new Chinese budget machines.
    Last edited by John11668; 16-06-2020 at 04:30 PM.

  5. #5
    When all the gear was in hand I went on to start fitting the leadscrews complete with bearings and ballnut mountings . These were to be simple billets of aluminium bored to take the cylindrical part of the nut then milled out to form a u shape allowing for relatively easy replacement if this became necessary. They were drilled and tapped for the ball nut fixings and drilled for fixings to the respective parts of the table . I had machine a seat on one face of the saddle, parallel to the dovetails to mount the X nut, and a pad underneath the saddle to fix the Y nut.
    Both of these seemed to mount simply enough where the old feed nuts had been .

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    These performed fine initially, and I was able to machine a few components with simple G Code routines which I had written myself. I went on to fit the homing switches, rebuilt the control panel and went on to add a few enhancements including a new breakout board to give me spindle start/ stop and speed control, and had a satisfying hour or two of play as I watched a milling cutter routing a pocket , but during that work it became clear that my aluminium brackets were not really up to the task.

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    The X bracket seemed not too bad but there was significant backlash in the Y motion due to two factors. One being that the nut was not a great fit in its bore so was relying on its fixing flange alone. The second was that the “feet “of the U bracket which bolted onto the underside of the saddle were just too small for reasonable bearing of the bracket on its mating face, and would not really accommodate decent sized fixing bolts . It was also clear that Aluminium being soft and quite plastic was not really the best material for this job. So back to the drawing board !
    Now as I have said before there were no calculations in this process. I went for the old principle of “give it plenty” and ordered a pair of cast iron blocks sawn from 70mm Meehanite bar. Then I set out to machine a new pair of ball nut housings which effectively would be as big as the table could accommodate .

  6. #6
    So onwards and upwards as they say.
    Material procured and I set off to turn rough cast blocks into some nice rectangular pieces . When I say “turn” I was being literal because the milling machine was tied up , and its high speed head would have been making sparks fly at 2000rpm, so my Colchester Bantam lathe was pressed into service to reduce the blocks to size and to bore good fitting locations for the ball nuts.

    In addition I needed to skim a larger seat for the “Y” nut so the toy Seig SX2 mill came into play too. I have to say that as a toy milling machine it made a pretty reasonable job, and in particular I found it was superb as a drilling machine when I came to drill and tap for the fixing bolts .

    The “X” nut block was a simple replacement, marked off and drilled using the old Alloy block as a template and jig. It barely cleared the underside of the table when fed from end to end , but by dressing a few high spots and lumps with the grinder, it then traversed freely. I may just take a light skim off the underside with the toy mill to ensure that nothing catches
    The “y” nut mounting was quite a lot more fiddly though, as I had to bore it fairly precisely in order to avoid shimming underneath it to align it with the ballscrew and nut . Nevertheless, and maybe more by good luck than good management , the nut slid quite easily into its bore with the block tight down onto its seat . Four M6 cap screws secured it firmly to the saddle and I intend to fit a couple of dowels for additional rigidity.

    So with the new blocks fitted this

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    Becomes this

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    And this

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    becomes this

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    All reassembled and now seems good and tight, so will now reinstate the homing switches , (I bought some more substantial ones from RS) adjust the settings in Mach 3, and give it a cutting test.
    I have to say that I am finding this very absorbing . Lockdown certainly has advantages when it comes to getting around to completing those projects which have been lying on the shelf for years .

    Then back to Cambam to see if I can make something useful happen
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    Last edited by John11668; 19-06-2020 at 09:51 AM.

  7. #7
    So it is now working again after a few hicupps and alterations to settings.

    Not sure if any others will be tempted towards a similar project. Albeit it is an economic route to a CNC function if you already have a decent sized milling machine to begin with.

    I like the idea because (as I said above) it saves interfering with the mechanics and drives of an existing machine, and in particular where modifications might detract from the value of an older and possibly much sought after machine.

    I can easily unplug my table and set it aside if I want to use the machine as a manual mill. Or I can even do a manual manual job with the CNC compound in place, using the Deckel mill’s own feeds and traverses, although I do recognise that rigidity will be a problem for larger jobs.
    I always wondered, if I converted my machine to CNC then what would I do if I needed to do some simple conventional milling, but no problem here.
    The table has a pretty decent work area for a first machine, probably a bit larger than a typical Chinese first step machine, so probably an easier project than converting something like a Seig x2 or a base machine of that order. Table length is good so lots of space for decent size workpieces or even a fourth axis if you are tempted to go that far.
    I have proved to myself that I can build a budget CNC machine. In my case the total cost of parts was a tad under £500 , So pretty reasonable and no massive loss if it turns out that I lose interest (which I honestly can’t imagine)
    I have thoroughly enjoyed the project and learned a lot too. So I can be much more confident in starting a second and maybe much more robust project.
    I may move on to a larger table, hopefully one with more space, and better put together.

    I am tempted by this one which looks more up to the job, with taper gibs. It would be nice to see one in the flesh though to be able to assess general fit and finish.
    It is not significantly taller than my first attempt so would certainly fit my on my Deckel table.

    This has certainly been a valuable project for me, a test bed to practice the skills which I am only beginning to grasp. I have certainly learned a lot in the process and it has been highly enjoyable as a project in itself. And as I hopefully progress to higher things, I will still have this as fall back option to test ideas. They say that “any old bike is good enough to practice on” so I will hang on to this even if I move to something more exciting.

    So if you are contemplating converting a sturdy old mill to CNC then I would certainly advocate this route. Not for everyone, but certainly works for me!

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