Page 2 of 2 FirstFirst 12
Results 11 to 16 of 16

Thread: How flat should my 2.5" x 1.5" rectangular support tubes be?

  1. #11
    Join Date
    Apr 1999
    Location
    Rock Hill SC
    Posts
    474

    Default

    [QUOTE=Chuck Keysor;202125]
    Brady, my primary objective was to improve my gantry's mechanical stability. It always just bugged me that I had to re-square the gantry every time I turned on my machine.

    You can buy 4130 steel tubing, angles, flats, etc. by the foot. It is used in aircraft construction because of it's strength to weight ratio. It is also "stiff". Once upon a time I tried to put a curve in a piece of 3/4 tubing with a conduit bender and found out that my 200 plus pounds were not enough to do the job.

    As you receive it it will be "Normalized" and is quite workable. After welding the area around the welds will be so hard that you almost can not cut it with anything you have in the run of the mill shop. You can anneal it with a propane torch and the information on how to is all over the web.

    This stuff welds like a dream. I would suggest, though, that you steer clear of the buzz boxes that HF sells. If you get a decent weld it is almost an accident. Pay a pro to get a decent TIG job and your project will be good for 50 or 60 years of service, just like an aircraft fuselage is.


    Take a look here http://aircraftproducts.wicksaircraft.com/category/aircraft-metal-tubes-channels-angles




  2. #12
    Join Date
    Jan 2004
    Location
    iBILD Solutions - Southern NJ
    Posts
    7,952

    Default

    Mild steel is fine. It's cheap, easy to work, easy to weld and the profiles mentioned should be straight in the lengths for this project. Just shim up the ones you have. Make sure you crown them both in the same direction...(up). You already overpaid for them, might as well just use them.

    Before you weld it all up, put the 1.5x2.5 pieces in place and mark out your bolt holes for the rails. If you got 3/16" wall, there should be enough meat there to tap it 5/16-18. Be sure to put witness marks on each rail support piece, including marking the TOP and which end & side the support goes. Then drill/tap off the machine using whatever you have. Be sure to use a punch to mark the centers and if you can, start each hole with a center drill to keep your larger bit from walking. The cup created by the center drill captivates the big drill and prevents it from walking. You really don't want to 'waller out' holes that are off after the fact. CHECK the threads on your rail bolts to make sure they ARE in fact 5/16-18 (just use a nut) because your setup is an oddball.

    Yes, ALL of those angle iron rails splay out when unbolted - so don't worry. Just get them true again when you assemble.

    Spreader blocks - 2x6 etc work great for setting the spread on both the 1.5x2.5 and rails. Cut 3pcs for each spread to help. (3pcs for between rails & 3pcs for between 1.5x2.5 tubes. Pipe clamps are also helpful.

    You don't need 4130 chromoly @ $45+/foot. I've been welding for 20+ years and have friends who bought the HF MIG for light automotive resto welding. The new ones have come a long way. It works just as well as any other fluxcore MIG. No bottle to put a deposit on, plus bottle rental every month like my shop. You don't need to have these parts TIG welded - just lay some weld beads down to lock it in square and be done with it. You're not welding up an aircraft frame...it's just a ShopBot.

    By the way, welding is best done ON THE MACHINE so you can verify that it is square and everything runs true. As soon as you take the gantry out of the shop, you have no way of telling if it is racked or 'out'. I would suggest having a weldor come over and do the work or just do it yourself. What one man can do, another can do, remember?

    In doing these mods to the machine, you really have to get over the 'preciousness' of the blue colored steel. It isn't special. It's just steel. Cut, drill, weld on it at will because it's just a pile of scrap if it doesn't do what you want as a CNC. Make it YOURS...then get some touch up paint and make it look all pretty again. ShopBot Blue = RAL 5022

    Good luck - hopefully you get in there and just knock it out so you can get back to the business of cutting again...If you lived closer, it would be done already!

    -B
    High Definition 3D Laser Scanning Services - Advanced ShopBot CNC Training and Consultation - Vectric Custom Video Training IBILD.com

  3. #13
    Join Date
    Oct 2009
    Location
    Elgin Illinois
    Posts
    696

    Default

    Hello Tom and Brady!

    Thanks Tom for the information on the aircraft steel. That was all new info to me since I don't have metal working experience.

    Thanks Brady for the added direction. The welder will be welding my X-car as it sits on my machine, as getting welded up and then finding something is off is the scariest part of this project. The tubing I bought is 3/16" thick, though I have to check my threads and my tap set.

    As to the blue paint, I am afraid I messed it up with all the filing I did to get rid of the cold-formed edge burs. (Had I just needed to file a few feet, I could have kept it nice, but I had to file every rail, on both sides, and got sloppier the more I filed. )

    Thanks again, Chuck
    Chuck Keysor (circa 1956)
    PRT Alpha 60" x 144" (circa 2004)
    Columbo 5HP spindle
    Aspire 9.0, Rhino 5

  4. #14
    Join Date
    Oct 2009
    Location
    Elgin Illinois
    Posts
    696

    Default

    As a delayed follow-up: Here are some shots prior to welding the rectangular steel tubing into my X-car.

    I didn't have a chop saw, and wasn't anxious to buy one. I simply plowed out a tight fitting groove in a 4x4 piece of Douglas Fir that would support each end of the steel tube, and at one end, I cut hacksaw blade guide kerfs, and had a block of steel on top of the tube to help guide my initial cut to make sure I started off perpendicular to the tube before the guide kerfs took control.

    I carefully dry fitted the two steel tubes. I went and squared up the X-car before the welding, but I forgot to scrape off the paint from the 3x3 steel tubing first. So I had to resquare the X-car again after scraping the paint and re-installing the steel tubing.

    Being used to working in wood, I planned to carefully (of course) the ends of each tube, to get a perfect/tight fit. And I no doubt wasted a lot of time doing this, as steel is not as easy to work as wood! My welder told me later, he would have been ok with a gap of up to 1/8" of an inch. Oh well, next time.

    I did NOT drill/tap any of the holes in the steel tubing before the welding. I was convinced that it would be safest to do all the marking and layout of the holes to support the Y rails after the welding is complete. And because the Y rails sit up, maybe 1/4" above the tubing, I will have to make supports (stacks of washers seems too easy) from some scrap steel tubing I bought, and I'll precisely fit those to make the Y rails exactly flat.

    Thanks, Chuck
    Attached Images Attached Images
    Chuck Keysor (circa 1956)
    PRT Alpha 60" x 144" (circa 2004)
    Columbo 5HP spindle
    Aspire 9.0, Rhino 5

  5. #15
    Join Date
    Oct 2009
    Location
    Elgin Illinois
    Posts
    696

    Default

    Here are the pictures of the welding the steel tubing onto my X-car, just to show some great sparks, then some follow-up shots. I went to my local big box hardware store expecting they would color match Rustoleum for me, but they only sold it as stock colors, so I didn't get a good match....

    By bearing down on the middle of the steel tubes, it is clear that this is much stronger than the aluminum supports that came with my machine. However, because the steel tubes are so long, even after welding, I found it easy to deform the gantry to be out of square, though I only did so gently, and it sprung right back to square when I released the pressure. And before replacing the aluminum, if I pulled the X-car out of square, it didn't spring back to square. I suppose having the Y-car sitting on the X-car will firm it up.



    I'll post pictures after I do all the drilling, tapping and mounting of the Y-rails. I hope to do that before the end of September...……. But I have to put the gutters on my house, which I bought last year, and only got part way done. Chuck
    Attached Images Attached Images
    Chuck Keysor (circa 1956)
    PRT Alpha 60" x 144" (circa 2004)
    Columbo 5HP spindle
    Aspire 9.0, Rhino 5

  6. #16
    Join Date
    Jan 2004
    Location
    iBILD Solutions - Southern NJ
    Posts
    7,952

    Default

    Sherwin Williams (not to be confused with Sherman Williams) can color match it to RAL 5022 if you want it to match exactly....However, what you have there is close enough and I doubt anyone will even notice, besides you. Last I checked, they can do a custom color in a rattle can for around $35 ea. Not cheap, but it's all you'd need and it will match perfectly. Take a motor mount or something to match up on their machine just in case.

    It should be pretty stiff & unrackable now! Drilling and taping the holes shouldn't take more than 2hrs...
    High Definition 3D Laser Scanning Services - Advanced ShopBot CNC Training and Consultation - Vectric Custom Video Training IBILD.com

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •