Finally starting new build 2’ x 2’ servo, ball screws, THK linear rails


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Thread: Finally starting new build 2’ x 2’ servo, ball screws, THK linear rails

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    Default Finally starting new build 2’ x 2’ servo, ball screws, THK linear rails

    So I am finally getting around to the new build. I have the parts and hardware with exception of some screws.

    Servos are Sanyo Denki 250 watt 32 V 10 Amp with 1000 PPR encoders
    Geckodrive G320’s to run the motors
    Ball screws are 1605’s
    THK SHS20V rails and bearing blocks (2 per rail)
    Structure will be aluminum extrusions 50 x 50 mm and 100 x 50 mm
    LinuxCNC will run the system
    Initial spindle... a Bosch Colt router, will change to a 2.2kw water cooled brushless in the future.

    I have the use of a Vision 4 axis (XYZA) to make parts like motor mount plates and such.

    I plan to put the Y rails and ball screws at the height of the X bridge above the table. The Z axis will have the rails moving with their bearing blocks attached to the X carriage making the Z assembly more rigid extending down with a bit over 6” Z axis travel.

    2 chunks of the 100 x 50 mm extrusion for the X bridge, and 2 more for the Y rails.
    The 50 x 50 mm extrusions for legs and table support.
    Vacuum table made of Corrian with 1” square slot grid (rounded corners) using neoprene gasket cut to length for the job. Pieces of MDF lay on the grid as spoil board (edges sealed) to hold the workpiece.

    More to come as I begin construction.
    Comments are welcome.

    Steve
    (Trapped on a small Caribbean Island)

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    Default Re: Finally starting new build 2’ x 2’ servo, ball screws, THK linear rails

    VGER,
    Hi there. How is your build coming? I currently have a Chinese 6040, had it for about 4 years, and thinking about building my own.

    I use Mach 3, no issues at all, and so mostly wood projects, signs, wine holders etc.

    I have a question, if you wouldnt mind answering.

    I've spent quite while researching kits. Here is a link on alibaba. https://www.alibaba.com/product-deta...7a9150f4z3NaTW

    Question though. What can I mount all this on? What have you done? I know it's probably a very basic question bit I realize everything has to be coplanar and I see all these guys who've made the DIY ones out of plywood etc. Seems to be an awful lot of play in there, especially towards the middle of the bed. How do you keep both linear guides exactly parallel/coplanar?

    Thinking about using the same components as you. Lastly, how much have you spent?

    Thank you,
    Alex



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    Default Re: Finally starting new build 2’ x 2’ servo, ball screws, THK linear rails

    Hi,
    seems like one critical difference between the two equipment lists....Vger is using 20mm THK square rails and cars whereas Woodlover is
    using 16mm round rails. World of difference in rigidity and cost.

    16mm round rails are about as stiff as well cooked spaghetti whereas square rails are the real deal.....even then there are design differences to be aware of.

    Craig



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    Default

    Quote Originally Posted by joeavaerage View Post
    Hi,
    seems like one critical difference between the two equipment lists....Vger is using 20mm THK square rails and cars whereas Woodlover is
    using 16mm round rails. World of difference in rigidity and cost.

    16mm round rails are about as stiff as well cooked spaghetti whereas square rails are the real deal.....even then there are design differences to be aware of.

    Craig

    Craig,
    Do you have a link for the ones you would recommend? Looking for a 4x4 build, solely for woodworking, but I want it to be heavy duty. Your spaghetti comment quickly changed my mind. I want mine strong, don’t kind paying a extra etc

    Thanks for your response



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    Default Re: Finally starting new build 2’ x 2’ servo, ball screws, THK linear rails

    Hi,
    that represents a problem, good square rails and heavy duty cars are probably ten times the price.

    If you are buying new then Hiwin (Taiwanese) is a good brand, good quality that won't break the bank. Just beware that there are
    hundreds of Chinese look-a-like rippoffs. To be fair some of them are actually quite good for the price but others are crap and poor value
    despite being cheap.

    This is on Ebay, the link is of no particular significance other than the rails and cars a new and genuine Hiwin. Your are looking for the EGR or HGR
    models as the heavy duty types. Note this link has 15mm square rails, rather smaller than Vgers but are still perfect for your needs.
    The industry standard sizes are 15, 20, 25, 30,35mm and up. For a machine like your 15 to 20mm is adequate.

    https://www.ebay.com/itm/HIWIN-EGR15...2355a5913d7910]

    As you can see these suckers ain't cheap!!

    Another possibility is second hand. the 15mm Bosch Rexroth rails and cars in my existing mini-mill are second hand and yet have performed perfectly for me.
    My new build mill is based on three indentical two rail sets with two cars each (6 rails, 12 cars) from THK, they are 20mm rails 650mm long and HSR (heavy
    duty) preloaded cars. They are brand new old stock, I paid $900USD including three day DHL shipping to New Zealand for them. They are superb!

    I got my original 15mm rails/cars from a Korean seller and went back when I wanted more stuff for my new build. I bought not only the rails/cars but
    also three superb indentical 32mm 5mm pitch ground C5 THK ballscrews in near new condition for $1000USD including three day DHL shipping.
    I can recommend this Ebay seller, I've bought multiple items from him.

    https://www.ebay.com/str/industrialpartsshop

    I suspect the problem you will have is trying to find rails long enough for a woodworking machine. My mill is MEGA stiff being all cast iron beds and frame
    but has only 350 mm x 350 mm x 350 mm travels.

    Craig



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    Default Re: Finally starting new build 2’ x 2’ servo, ball screws, THK linear rails

    Hey there woodlover. Looked at the alibaba link, seems like a great price for what it is, especially the water cooled spindle.

    The lengths of the rails in that kit will limit you to about 40” of travel on the x and y. Ya gotta remember those bearing trucks take up space on the rails.

    Joeavaerage is right about the THK linear rails being more rigid than the round. And yes, they are more expensive. The SBR16’s are quite usable depending on what they are mounted to. A lot of folks use MDF and particleboard and some turn out quite well. Just remember stiffness is the key to success.

    I picked up the THK rails and blocks and the ball screws about 4 1/2 years ago on eBay. Total was about $1,200. The extrusions I picked up at an electronics recycler and were the framework for a custom electronics cabinet, and paid just over the scrap aluminum price at the time.

    My first machine used round bar and ball bushings. 8 x 8 x 2 inch travel. Very small, but worked for making PC boards. Machine #2 was 24” X 24” X 8” with a turntable (A axis) using hardened round rod (diy supports) and skate bearings.
    Machine #3 was 48” X 96” X 6” with linear rails and ball screws scavenged from a scrapped out laser cutting machine. Those linear rails and ball screws were monsters! The y rails were about 9 feet long and weighed at least 80 pounds each, and the ball screws were even heavier. Built that machine for a friend that had a counter-top business.

    Now retired, got the house built, and most of the finish-up projects out of the way, so now have a little time to build the next one. Been about 4 years waiting. I did modify and reconstruct an older Vision engraver to use for making some smaller parts for the new machine. The Vision engraver does have a 4th axis bed, head and tailstock, similar to a lathe but very finely stepper controlled. I made a small t-slot table for it to make parts with.

    My software is older version of Vectric V-carve pro with the Photo-V-carve package. I have exclusively used LinuxCNC as machine controller on each one of the machines, with dedicated PC’s running on UPS battery backups.

    On keeping everything coplanar. Get the first rail mounted just as square as possible in both planes. Then loosely set the second rail with the bridge or carriage in place at one end and snug the second rail at that end. Move the bridge or carriage to the other end and snug it down, then to the center and snug there. Then the rest of the rail gets snugged down.
    That’s the quick and dirty way. Shimstock, dial indicators, and long bars and bar sag calculations...... is another. ??

    Best of luck and keep researching.
    Steve



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    Default Re: Finally starting new build 2’ x 2’ servo, ball screws, THK linear rails

    Woodlover, one other note about using MDF or plywood or particleboard. If I were going to build a machine with those materials, I would construct long boxes to mount the rails to. Maybe about 6 or 8 inch square and a bit longer than the rails, so you have some room for ball screw bearing mounts and motor mounts. I’d put the Y rails at the height of the bridge with the ball screw down one side and use small steel cable strung over bearing rollers around that level in such a manner that it locks the other side in step. You would need to put a piece of material across each end of the machine to keep the Y rail boxes spaced rigidly. I’ll sketch the scheme out if you need.

    Steve



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    Default Re: Finally starting new build 2’ x 2’ servo, ball screws, THK linear rails

    Found a sketch.... similar, works for drafting horizontal bars...
    Finally starting new build 2’ x 2’ servo, ball screws, THK linear rails-7686f69a-e934-41d5-82fb-ac9cc2725fbe-jpeg



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Finally starting new build 2’ x 2’ servo, ball screws, THK linear rails

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Finally starting new build 2’ x 2’ servo, ball screws, THK linear rails