#241
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Nice work
I must recognize that you inspire me a lot. Specially the way to fit one piece in other. Welding becomes a kid's play.
Here are a pic of my table: |
#242
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Hey Marius
Correct, puzzle connections make it very easy to weld things up true and straight.. Your new table also looks good, looks a bit small though, are you downscaling from full size to smaller size? |
#243
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Yes it's a small size 800x1600 working surface but is for small pieces and will have an indexer.
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#244
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Very nice, I'm also looking into adding an indexer at some point, but it's still on the drawing table so to speak.
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#245
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Did you modeled it before assembly? that size, maybe a little smaller, is what I have in mind, if you can share it it would be great. Very Nice too!!
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#246
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Hi Kim,
I am slowly getting closer to starting a build and the more I look at this thread, the more convinced I become that linear bearing slides are the way to go. I was wondering if you could tell us what size your used for each axis? SBR12 or 16, and maybe even 20 would seem to be too small for the X-axis, so I would guesstimate that you used either SBR25 or 30 for the X and Y, and 16 or 20 for the Z-slides. In retrospect, given the performance of the machine, would you have gone larger, or smaller, with those slides? And why? Also, three meter lengths of slides, if even available, are exceedingly expensive so most people just butt shorter lengths together. If you used this latter configuration, did you just simply butt them together or did you have the opposing ends precision bored (usually in a lathe) for dowel pins? Cheers, Brian Taxachusetts |
#247
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Regarding the linear bearings be sure to watch this very informative video.
It will help you see the needed precision for mounting rails and their use. http://www.youtube.com/watch?v=rq4Pis6Zhf4 |
#248
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Quote:
Thanx, Brian |
#249
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Quote:
The rails I used for my X axis is 20mm rails, and the y and z axis is only 16mm rails.. They are more than strong enough to hold the forces of the machine when in motion and when cutting. After I have fitted my gearboxes, my rack and pinions and my ballscrew, the performance of the machine it self have been significantly improved... I have not yet had time to do some good quality testing yet, because of my new job, so I can't really tell you about the precision, but I expect it to be something around 0.1-0.3mm precision on all axis.. Which is more than enough for my needs. The X-rails by the way is full length of 3meters, no butting here... |
#250
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Hi Kim,
how about dust getting into the linear bush? Linear bush are notorious with thier dust proofing characteristics as far as I know. |
#251
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Ken
That problem should you be able to prevent by adding some good dust extraction to the machine. Right now I have none, so I dust off as much as I can. But so far so good, no dust in the bearings yet. There is a good scraber ring on the bearings, so dust do not actually enter the bearing. But still good dust extraction is always a good idea. |
#252
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Quote:
I don't know exactly how you would do this for a CNC router, but in the machine tool world, the felt is cut to closely match the shape of the ways and a brass cover, of at least 16 gauge thickness and clearing the machine's ways (or, in this case, the linear bearing) by no more than 0.060", or a nominal 1/16", is also fabricated. Provision then is made to affix this sandwich to the block using a minimum of three machine screws. For machine tools, the felt would be further saturated with way oil, but that would attract and hold MDF dust and make for an interesting combination, to say the least - who knows, it might even work better. Furthermore, I'm not sure how the bearing blocks would tolerate the oil. Rigid felt is available in sheets in several thicknesses and of varying stiffness from industrial supply houses. In the States, McMaster-Carr or MSC are good places to look. Brian Taxachusetts |
#253
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I really dont think you need to be too concerned regarding dust ingress into linear bearings, if it was much of a problem the big iron manufacturers would have found a different solution, I cant recall a single big iron machine (SCM, Biesse, Weeke, Multicam etc etc) using anything else but linear bearings. I had a Biesse and an SCM working with copious amounts of MDF dust over a six year period (2x 8 hour shifts 5 days per week) without any negative effects - Note regular servicing and greasing was done (SCM had auto centralised greasing system - Biesse was manual)
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#254
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Had a clog once, after oiling the wheels on Z axis in the same day I cut MDF and styrofoam.
Foam being driven by static charge flew onto wheels and slide, mixed with grease and finally cemented with fine mdf dust. I left out the cleaning after work that day, and in the morning it was so sticky, barely able to move. So proper dust extraction, cleaning of guide ways and motion systems is essential. No way that unattended machine can work covered in dust. Metal working machines have all the guides well hidden and lubricate them all the time automatically so they last a long time. |
#255
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I wiped my machine down about once a week. A good liberal spraying of slicktop (table saw top) on my rails and rack kept everything slick and mostly clean. When cutting foam, it was a constant effort to hand vac the areas of the machine the standard dust collection.
I second the comments - no worries....just regular attention to keep it all working. |
#256
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You can also buy double seals and scrapers in addition to the stock rubber seals.
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#257
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Hi Kim
I also live in Denmark and we have already built a Mechmate in our workshop. However we built the rails in alluminum and now want to make them in steel. Did you buy your rails and can you share the contact? Or did you make them yourself and can you share the plans or your angle skate? |
#258
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Hi Drew.
No secrets as to where I bought my linear rails. www.slidesandballscrews.co.uk Price was fair enough, and he delivered in full length to me. Me a bit carefull though, his packaging could be better, thank god for the materials ability to flex a bit when you mount it. |
#259
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I'm a mad builder.
Sold the last one and am in the progress of building again.
Follow the thread here. http://www.cnczone.com/forums/cnc_wo...x8_router.html Here's a look at the present look. I bet one person inhere can see something familiar. |
#260
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That looks very nice, I like it.
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#261
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hi kim me also in the process of building something like yours
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#262
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The main reason for the increased cost on my own design, is primarily weight and rigidity.
My machine weighs in at +1200kg and is so strong built that it will not have any chance of flexing what so ever. Even my gantry weighs in at more than 180kg. The Gantry beam it self weighs a massive 90kg. |
#263
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Nice looking machine Kim...
Although I don't think a MechMate for the same size weights much less at all. If I was to guess my machine is probably closer for 2000lbs.. Maybe I am completely wrong about the weight. |
#264
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I did calculate the weight of my mechmate which was no more than around 6-700kg so I think there's a big difference in weight. My x axis beams weighs 180kg pr side which is the same weight as both the longitudal beams on the mechmate. Already there i'm up 180 kg on the mechmate.
But still 4-500 kg is a big difference in weight. |
#265
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Kim, nice machine!
On your heavy machine, do you see real improvement over the cut quality over light duty MM? |
#266
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The major difference I see is the ability to not have any chatter on circles of any kind, other things like errors are not as hazardouz on mine as on the MM. If I accidently make a plunge error, so the bit is too low, then I don't have to fear that the gantry comes of it's rollers or anything. In my initial setup of my Z axis, I accidently lost steps trying to peck drill with a endmill. When it wen't to the next hole it had lost enough steps so it was a bit over 1/2" into a 3/4 sheet of MDF when it suddenty pulled my 5mm endmill in the sheet at 12000mm/min, the only thing that moved a bit was the test sheet, the cut was actually allright and the endmill still lives to this day.
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#267
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I have truly enjoyed reading your build, and you have a great machine well done!!
Just a quick question did you have to do any milling to any of the gantry on the ends where they join to the uprights from the rails in order to have a true gantry? |
#268
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No I did not do any milling of the ends where they meet the uprights. Having things like that done here in Denmark, is quite costly...
I have shimmed the Z axis upon mounting it... |
#269
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Please post some photos of your cut quality, especially curves to show chatter or lack of chatter.
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#270
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There is next to no chatter at all in circles and such. But at very low speeds the bigger motors resonate a lot, so it might give a touch of chatter at low speeds, but I'll try and change the PSU and give them a little less power, right now they get 70V DC, so it's quite alot.. I'll try with 48V instead.
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