New CNC build using 80/20 extruded aluminum - Page 5 - Router Forums
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post #41 of 47 (permalink) Old 08-18-2011, 08:06 PM
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Default So you are are saying that You would't add 2" to the X axis?

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If you only plan on cutting wood, not aluminum, then it shouldn't be a problem as far as the extrusion goes. Some have said you shouldn't count on the 1/4" cold rolled steel for strength, but I do believe it helps on the Y-axis.

Nonetheless, 80/20 has a free beam calculator for their extrusions, and there is a short vid that helps explain it a bit:
80/20 deflection calculator LINK

One thing that could be a problem is the lead screw on the X-axis. They say that 48" is about as long as you want to use for an ACME screw because any more than that and you get screw whip. Basically, as the ACME screw spins very fast, it will start to wobble because of centripetal force and starts to cause problems. That is why you want a multi-start, such as 1/2-10 5-start lead screw, so it doesn't have to spin as fast.

By adding 2" on the X-axis, you are starting to get near that 48" mark and that is where most will recommend going to a rack and pinion instead. CNCRouterparts sells the r&p here (watch the video also): Rack and Pinion Drive, Nema 23

I will say that some have used 48" ACME lead screws and haven't had a problem. If you were to do that, you may not want to cut at 150 ipm, you may want to start slower to be on the safe side.
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post #42 of 47 (permalink) Old 10-17-2011, 06:10 PM
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Thanks for posting your machine. It did inspire me to make my own. Should be done fairly soon. I'll post a pic when I get a chance.
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post #43 of 47 (permalink) Old 06-22-2015, 12:25 PM
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i used t slot for alot of my main structure, i found 1" angle bolts to it really nice as guides, for v goove bearings. Also carriage bolts are a good alternative vs tslot nuts that can add up in cost. just my (maybe) helpful tips lol plus t slot just makes everything look so much cooler haha
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post #44 of 47 (permalink) Old 11-10-2017, 06:33 PM
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I commend those who are building their own CNC and wish you good luck with your projects.

In looking at prebuilt models, there seem to be two different construction styles; welded and screwed. Since you are using 8020, you fall into the screwed together construction style.

My question is, what are you doing about guaranteeing the screws don't come loose after many hours of use and lots of vibration? Any special locking nuts or are you using Locktight? Red or blue?

I also teach AR-15 building and Locktight is one of our best friends.

Thanks,
Gary Salisbury
Sunny San Diego, Kalifornia
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post #45 of 47 (permalink) Old 11-10-2017, 07:29 PM
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Originally Posted by Gary Salisbury View Post
I commend those who are building their own CNC and wish you good luck with your projects.

In looking at prebuilt models, there seem to be two different construction styles; welded and screwed. Since you are using 8020, you fall into the screwed together construction style.

My question is, what are you doing about guaranteeing the screws don't come loose after many hours of use and lots of vibration? Any special locking nuts or are you using Locktight? Red or blue?

I also teach AR-15 building and Locktight is one of our best friends.


The design of 8020 tslot makes the edges of each slot is canted slightly inwards. When a bolt is tightened, this provides a locking feature, almost like a Belleville washer. I have not noticed any loosening of bolts on my machine. I have lock washers on other bolts which do not engage tslots (I.e. steppers, guide rail bearing blocks, etc.).

The control software should accelerate and decelerate axis motion, and speeds and feeds should keep motion smooth. There will obviously be vibrations, but hopefully not the kinds of shock loads present in a firearm.

Tubular latex pressure vessel configuration engineer
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post #46 of 47 (permalink) Old 11-10-2017, 08:25 PM
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I used Nylock Nuts on bolts which do not engage tslots.
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post #47 of 47 (permalink) Old 11-22-2017, 07:03 AM
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Default 8020 Turkey Day 15% off deal - 4 days

8020 is having a 15% off deal going you Turkeys!
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