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# Thread: How is it so far?

1. ## How is it so far?

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2. Well fwiw, here is my \$0.02.
It looks like you are using 1530 extrusions for you outside frame and it looks like you are spanning about 6'. I think this will flex more than you would like (I know it would be more than I would like). I would have made it more robust. Here is a link to automation4less. They have some great pdf files that will easily allow you to figure the amount of bending you can expect.
structural aluminum extrusions, TSLOTS, T-Slots, 80/20, Parker, Item, IPS, slotted extrusion

As far are autocad, I'm sure there are people who swear by it. I tried it once and found it awkward and hard to learn. You couldn't give it to me. I use TurboCAD. It's easy to learn (relatively) and cheap. It will probably do all you want and more.

Good luck.
Rick

3. Hey RicknBeachcrest

I was looking into figuring out how much flex my machine will and can't figure it out. The actual measurements for my machine is 60"x39" and the height is 39". Can you help me determine how much flex it might have? What would happen if it has to much flex? Is there anything I could add to it in order to make is stiffer? I'm also looking into TurboCad because theirs more tutorials for it. What TurboCad you think I should get so many types?

4. Max. Deflection is in inches
° "F" or Force is in pounds
° "L" or Length is in inches
° "E" or Modulus of elasticity is in pounds per inch squared
° "I" or Moment of Inertia is in inches 4
° "W" or Weight is in pounds per inch

MAX DEFLECTION =
FL^3
----
48 EI

lets say the force on each side is 200lbs
length is 60"
modulas of elacticity is 10,000,000
moment of inertia is 1.877 for Tslot's 1530 oriented with skinny side up.

This is in the attachment, courtesy of Automation4Less.com (Great company by the way, I bought all my extruded aluminum from them).

Just do the math. So I get about .048" of deflection in the middle.

Ways to reduce the deflection? Reduce the span or change the dimension of the material used.

I've been using TurboCAD deluxe v12 for years. It does everything I need and then some.

Here is v15 for just \$15. Can't go to wrong at that price.

I also included a photo of my machine. It is about 24" square.

My number one suggestion for anyone just starting out is to spend a couple hours each night reading this forum and do this for a couple of months. I book marked everything I felt to be relevant to what I wanted to build and then I re-read it. If I had any questions on a particular aspect of someones build, I would post it on their build log.

Good luck.
Rick

5. All good points and advice. A few points I want to make though.

Using dual rack and pinion drives on the gantry, you can add more legs to support the table, so flex isn't as big of a deal.

99%+ of what gets machined on a table like yours is way more flexible than the table itself, so with a spoilboard that's been machined flat, and the stock clamped down, any flex will not show up in the finished parts, probably even in up to 1" thick aluminum.

I have a very similar table, shorter x and single y drive, 60"long 1530 rails, you can see the sag in the table, has never EVER been a problem with the finished parts because of it. If I was machining molds out of 4" thick aluminum it would be a problem, but that's way out of the scope of the rest of the machine anyways.

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6. Hey RicknBeachcrest

Thank you so much for taking some of your time to post valuable information for me. I think what I might do to reduce deflection is to add 2 more legs towards the middle. Hopefully that will help reduce it. I'm going to purchase TurboCad for that price you can't go wrong. But the next parts I'm going to buy will be the rack and pinion assembly. But in the mean time I'll have to learn TurboCad

PS I actually bought TurboCad v18 for \$16.05 :banana:

Thanks for reading my thread. I mostly want to cut airplanes out of balsa and other light wood so hopefully the deflection should be to much of an issue. But if could find 2 more pieces for a good price for the legs I'll get them. Thanks

7. Good choice on Turbocad, I have been using it since 7.0 or so, 2003 I believe, now using 15 deluxe. It does everything I need it to do for 2D work, and is super fast once you learn the keyboard snap shortcuts. Sure is a bargain. I use Rhino3d for the more complicated 3D stuff, but if your used to designing planes on paper, turbocad will be a breeze.

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Well i have no experiance in anything not even designing airplanes on paper. Everything i'm doing i'm learning as i go but love every minute of it. I want to build rc plane but i don't even know how to fly. Their was this guy that was going to teach me how to fly this summer but i never was able to get in thouch with him. Oh well maybe next year. I was wondering how were you able to align the holes down the middle of the metal rail? How wide should i buy metal rails?ie how much should the metal stick out from the sides in order for the bearing to ride on them.

9. Gotta love the 8020. Stiff, light, and straight... Good luck!

10. The good thing about using 8020 being able to buy pre-cut pieces. I'm not to good with power tools so that's why I decided to go this route. This stuff is so easy to work with and your imagination is limited by your pockets

11. As someone said, you can simply add a leg in the middle on each side if the concern of bending bothers you much. My machine is on a wood table, so I have no doubt there is bending. And it's on a wood floor which no doubt gives here and there a bit due to the weight. In the end, if you surface the worktop, and you have your x,y and z straight and squared, things will come out fine.

Look forward to seeing the rest of the build as it goes. BTW, if you are basing things off of mine, design your Y to use the R&P drive instead of acme screw. Much easier to clean and maintain... changing the acme nut for the Y on mine is a major job and not at all fun or easy.

12. Arbo,

Thanks for your input I really appreciate it. Thank you for the heads up on the y axis I will definitely do R&P all around. I make deliveries to different companies everyday. As I'm making the delivery, I'm always on the look out for parts that I might be able to use for my build. Well I went to this metal and thread shop and noticed they had plenty of metal, so I decided to ask how much. Well for 2pcs of 1/4"x3"x5' with 5/16" holes punched right down the middle they only charged me \$40. I want to paint the middle of the rails red to match the other parts. My question is do I have to do anything to the metal where the bearing will be riding on?

13. If all your doing is planes check out sketchup 8 and sketchucam plug in all free
Google phlatboyz. I found it to be a great tool for open source freeware

14. RMHCNC

Thanks for the your suggestion on sketchup 8. I bought turbocad 18, because I was able to purchase a tutorial for drawing up planes. I will try to just learn one program in order not to get confused. Hopefully turbocad will be a good program to learn. Learning two programs might just be to challenging for me.

16. yeah you definitely want cold rolled.

17. Well I just ordered the cold rolled rails for the x and y axis. I have a drill press and will like to start using it. I will like to build a drill press table in order to drill the holes on the steel. Any one have any ideas on how to drill the holes on the steel without a table? They need to be straight and in the middle.

18. I scribed the center, center punched the hole locations, started with a 1/8" pilot bit and opened them up to just over 5/16" so I would have some wiggle room. Wasn't too bad.

19. Your table looks awesome! I am at about the same point in my build. You can see it on my site. I should have my screws in the next couple days, and my linear rails within the next two weeks! Have you figured out what size motors you will be using? One thing I am looking into for rigidity is an epoxy/granite type solution to fill the voids in my extrusion. I look forward to seeing your progress, and have bookmarked your build!

20. Rusty13jr

I just received my cold rolled steel yesterday and will like to figure out a way to drill the holes. I like dylwad idea which I'm going to try on my old piece of hot rolled steel i bought. As far as the electronic I'm going with the nema 23 gecko system from cncrouterparts because it's plug and play. It's going to be a dual rack and pinion systems and from the answered i have received it should me just fine. I'm just waiting to see if theirs a sale going on soon before i buy. I'm going with the gecko system because of it's good resale value just in case one day I'll build another bigger machine. I will keep an eye on your machine also it's looking good. The 8020 stuff does get expensive that's why it doesn't have more support but hopefully it should be good enough. If it's not good I could always add 2 more legs.

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