Hello Charles,

I'm sorry, I thought this was the C-Beam thread? Would you please point me as to which thread I should post to?

Thanks,
Alex

 

Thanks for the reply I have the nema 23s and the arduino and gshield was looking at a 24v 15 amp power supply do a lot of scroll saw cutting on 1/8 and 3/16 aluminum, getting harder with fingers that don't work like they use to. Thanks again

 

You will need an Arduino running GRBL $25. A Gshield $50. 6 amp or more power supply $30. A router...I am using the Dewalt DWP611 $120. Software can all be had for free to get up and running. I am using GRBL panel to feed the Arduino/Gshield. I have been using Estlcam to turn drawings into code for the machine to run.

 

I know it has been mentioned before, but I am to the point I am finally cutting, but am noticing a fair amount of deflection in the Z when pushed or pulled on. I was thinking of trying to tighten the eccentrics a bit more but don't want to put extra wear on them if it won't really help. If it is just the way it is, then I can deal with it and just go nice and slow. I realize this is a $500 kits so I'm not expecting mil spec, but if there is something simple I can do to take out some of the slop...I'll take what I can get.
UPDATE: Unless others have noticed otherwise...It. seems that while a great value for the money...there are some areas that I may work on to build some extra rigidity into the machine. I noticed a fair amount old flex in just about every part of the machine. Looks like my first aluminum parts may be for these cbeam machine itself =) Can't wait!!! Hahaha

 

Yes, there's a fair bit of deflection. My testing shows the weakest link is the extreme wheels.

Tightening the eccentrics a bit more doesn't reduce the deflection because small amounts of deflection are roughly proportional to the applied force, i.e. it doesn't stop deflecting after a certain amount of force. In fact my testing shows too much tightening of the eccentrics will result in increased backlash. If you try to rotate the wheels by hand to check tightness, you don't want the wheels to spin freely because that means there's no contact. However you should be able to make the wheels drag against the v-slot as you spin them by hand. If you can't then it's too tight. You want them to just barely rub against the v-slot.

You can reduce deflection by creating new plates for the wheels that push them further apart. The parts store now has the double wide gantry plate, but that only spreads the wheel further apart along one axis. For example the wheels on that gantry are on the inside of the c-beam channel, just as they are on the original gantry. So although the wheel are spread apart in one direction, they aren't in the other direction. Putting the wheels on the outside of the c-beam would help. Deflection caused by torsion (i.e. rotation) is inversely proportional to the square of the distance between the wheels. If you want to cut this type of deflection to 1/4, then you have to double the distance between the wheels.

(Edited to correct relationship of deflection caused by wheel distance.)

 

You can't see a few or tens of thousands of deflection. It must be measured. But that doesn't mean it's not significant.

 

280mm Overall Length x 20mm Overall Width x 85296564 - MSC
if you buy these your problems will be gone, but it's going to cost you.
I have cut a whole bunch of aluminum on mine no problems at all.
Bob

 

Thanks for the replies guys. I am sure quality cuts can be made as long as the machine is not pushed very hard. I just wanted to make sure I was seeing what was normal for this machine.

 

I hope I didn't get us side tracked with the shortcomings of the C-Beam Machine. When I bought the machine I had mixed expectations. I think while some things could be better...overall the kit went together pretty easily. For the money it can do a lot of things that will let me improve the C-Beam machine itself as well as create new things and improve other older projects. The machine is a great jumping off point that will remain useful even after some have moved on to larger and or more powerful platforms. Check out Kyo's video on his idea for updates to the machine that reuses almost all of the parts from the C-Beam machine.

 

Use on x and z?

 

Dave,

See my post #790 Jan 19, 2016 in this thread. I've isolated it and most of the deflection shown in that post is from the wheels.

As Jim stated, we don't need to get side tracked with the shortcomings of the C-Beam. At the same time it's ok to acknowledge limitations. This ultimately leads to improvements - some of which I'm in the process of working on.

 

Mark, how are you measuring the deflection on your C-Beam?

 

Help me, where would I find "Kyo's video on his ideas for updates...."

 

I assume someone has mentioned it, but is there a fix for fact that the center of the large wheels is .71mm farther out than the center of the mini wheels, and to make both in the center of the C-Beam groves on the Z axis, the spacer for the large wheels should be 5.3mm if 6mm spacers are used for the mini wheels? Either that, or make a .71mm CB in the gantry plate where the large wheels attach.

 

Accord

According to the dimensio s of the wheels, they differ by 1.43mm, which means either making the large wheel spacer shorter by .715mm or adding a .715mm spacer to the mini wheels so that both edges of both type of wheels contact both edges of thier respective grooves in the Z axis C Beam.
Adding a 1mm shim to the mini wheels would be a good enough solution.

 

As Rick says, you need to go by the bearings, not the wheels. The "sidewalls" of the wheels don't touch anything.