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  1. #221
    Quote Originally Posted by AndyGuid View Post
    Agree with you 100% Andrei, I am totally sick of hearing "The evidence shows . . . . . " going unchallenged!!!

    Downunder "they" have a thing about MSG, which to me is the best thing since sliced bread so I use it whenever necessary.

    Where's the friggin evidence?

    Similarly, I've been deprived of eggs and butter for so many years because of "their" hysteria!
    MSG per gram has less sodium than table salt - it is the sodium that causes problems- so MSG is better than NACl !
    Albert Einstein may have been a genius, but his brother Frank, was a monster

    Having just moved to Windows 10 (which is crap) My stress levels are through the roof !!!

  2. #222
    Sorry for my uninformed reply. On a quick google search it looked like a Dremel.

  3. #223
    Your carving lack of detail at the bottom edge, looks as though the wood was not set level to the XY plane. So I would check the bed is parallel to the X and Y axises.
    Albert Einstein may have been a genius, but his brother Frank, was a monster

    Having just moved to Windows 10 (which is crap) My stress levels are through the roof !!!

  4. #224
    I just found out about the tramming thing and will do so in the next days. The bed was milled with a 10mm end mill, so I guess it should be somewhat parallel.

  5. #225
    Quote Originally Posted by Radu_Andrei View Post
    Neale , I have no clue how you can reach 4500 mm per min, as mine stalls at 3400-3500. How much does the gantry weigh? Could you please post a photo.
    Andrei, take a look at this thread. I have described my machine there, so start with that and ask questions if there is anything else that you would like to know. Quick answer to your question is about 40Kg, I think, but the mass of the gantry is not that important to speed but it does affect maximum acceleration (and deceleration).

    I spent a lot of time aligning the ballscrews and the linear rails.
    Last edited by Neale; 06-12-2018 at 11:49 PM.

  6. #226
    Just finished reading the build log: That.s a great library of information. Thanks for that.
    Unfortunately, I did not find what I was looking for. My gantry as seen on the first link from post 218, sits on two identical 24mm aluminium plates, so no need for epoxy levelling my my case, although in the absence of a flat reference surface, this sounds the way to go.

    I find straightforward the alignment of the rail as paralel and square to the other axis (4 holes test), but I have no clue how to make them coplanar. I just cut the steel tubing tiny segments that hold the one upon which the rails are mounted, as equal as I could, then when only the rails were fited I adjusted the whole thing until I did not feel any resistance, but they might stil not be complanar, as is the linear bearing have quite a tolerance. Except with a construction level, I have no clue how to check that. Then mounted the ballscrew , added the coupler and a 14mm rod on the other side, and turned it with the tips of my finger the whole distance, while adjusting the up/down amd right/left screws.
    It seemed ok at the moment.

    It is failry easy the release the bolts and redo the calibration, but I don.t know what I would do differently.

  7. #227
    Self correction, updated for today. Although the rails seemed a while back paralel enough, they are not. I have a 1-1.5 mm error on a 1.5 meters run. Anyway, I.ll take the y axis apart in the next days, and assuming you are in my shoes, and you plan to allign the y axis from scratch, in what manner would you do it? Where to start first? Paralel, perpendicular, coplanar? In what order? And how would you do it? The method, please. :)

  8. #228
    The requirement is for the two rails to be absolutely parallel, both horizontally and vertically. To deal with the second of these first - I ensured that the two rails both sat on "perfectly" level surfaces. This meant that I could adjust each side separately because "level" is a measurable quantity. I actually used a precision level bought from eBay for the purpose. Probably a bit more sensitive (and therefore more difficult to use) than necessary, but it needs to be better than you can achieve with a builder's level. I had used epoxy on my rails, but did not achieve a perfectly level surface all the way along so i ended up using shims to compensate. With the aid of the precision level, this was not too difficult. Note that I have talked about leveling each side individually. I deliberately built in the capability of dealing with two rail surfaces that were not coplanar. Other people talk about using a bridge between rails to achieve coplanar surfaces which is a good idea if you can do it; I preferred to allow for a small error in height (about 1mm, measured with a builder's level).

    The other requirement is that the rails are parallel in the horizontal plane. Actually, getting them parallel is the easy part. The difficult part is bolting down the first rail absolutely straight. I used a straightedge as best I could, although it was not the full length of the rail. However, for a woodworking machine I decided that this was good enough. If I figure out how I can do better, I can always adjust it again. Once the first rail is in place, you can use the gantry to set the position of the second rail. Lightly bolt it in place so that it can move sideways, set up the gantry, and slide it along. This will bring the second rail into alignment and you can tighten the bolts as you go. This is actually one of the methods described in the Hiwin catalogue, if you cannot machine accurate reference edges into the machine structure. When you have finished, you should be able to move the gantry the whole length of the rails with very little effort. Note that the bearings actually move more smoothly if they have some load on them. These profile rails and bearings are amazing. When I was setting up my machine, at one point I had the bearings fitted to one end of the gantry while I was adjusting the second rail. I tried to support the gantry weight while the second rail was not in place but I realised that I had forgotten to do this. The end of the gantry (probably roughly 20kg?) sagged by no more than a couple of millimetres, while it was held at one end only by two Hiwin bearing carriages.

    I also spent some time aligning the ballnuts and ballscrews. I started by ensuring that the ballscrews when held in the ballnut were parallel to the rails both vertically and horizontally. Gantry in the middle of its travel and ballscrew screwed into the ballnut so that it was more-or-less balanced, and no bearings fitted. I could then measure the level of the ballscrew (spirit level) and distance from the frame (as the rail was pretty much parallel to the side of the frame). I then converted these measurements into the size of shims I needed behind the ballnut mounting plate to bring the ballscrew into alignment. Once this was done I could fit and adjust the bearings at each end by turning the ballscrew (I actually used a cordless drill to wind it backwards and forwards) to bring the ballnut as close as possible to the bearing, then tightening the bearing mounting plate fixings with the bearing positioned by the ballscrew. Repeat at each end, then test. It took a while to achieve all this, but it did work.

  9. #229
    Hi Neale. Thank you for the comprehensive reply. It is so valuable, as I did think about this issue all day and could not come up with a method as yet. I was thinking of taking the time to build a large precise construction square, so I can figure out if the gantry is perpendicular with the y axis rails, but then, in order to get the most precise reading, I needed to have a tool that touches both x and y rails at the same time, and it is a quite a pain for me to build such a tool with enough accuracy, as there is a significant difference in height between this two sets of rails.

    Regarding your post, ˇˇThe difficult part is bolting down the first rail absolutely straight.ˇˇ, before doing that, is it not necessary to set the y axis linear bearings/rails absolutely perpendicular to the x axis rails?
    All holes for the bearings, rails, steel tubing, aluminium plates, are a bit larger than they were necesary, so sideways adjustement is not a problem, but I.m not sure if I should set the bearings in relation to the x axis first or the y axis rails and do the bearing afterwards.

    A precision level cost here 100+ euro, and even if I.m tempted to discuss this option with Santa this year, I.m a bit concerned that, except for this job, I.ll never use it again. Thanks for the tip, though, I did not even know this tool exists until today.

  10. #230
    I don't know if this would work or even what level of accuracy you would get, but what about a water level ? You could make one out of clear plastic tubing it is easy enough to make one that will do 4 places, just by adding in T's and more tubing. That way you could put your X rails coplanar, for a start.
    Albert Einstein may have been a genius, but his brother Frank, was a monster

    Having just moved to Windows 10 (which is crap) My stress levels are through the roof !!!

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