40mm finnish birch plywood CNC-router

[fretman_2]

Could you move the Y lead screws onto the sides? You'd be preventing them from getting lots of wood dust. That would enlarge the footprint of the machine a little, but would take advantage of the high walls you have supporting the Y trucks.

[hautamak]

Thanks for critic!

1. yes that would greatly help with maintenance! Didn't thought that.
1a. there is no threads showing because I wanted solidworks simulation to be as smooth as possible. those are 8mm trapezoidal threads.
2. At the moment it's 200mm should I separate them more?
3. gantry is now 70mm and will be torsion box. Is 70mm too narrow?

[hautamak]

Maintenance will prpbabpy be a pain with the holes. If the holes are bigger to help maintenance, it will make your gantry side less stiff.

+1 to put the leadscrews outside.

How big impact let's say 100mm wide and 40mm tall hole would make?

[hautamak]

And more questions, I have different microstepping options in my stepmotor drivers and googled, but didn't find straight answer which options are best. Should I disable it completely?
Also, can the gantry sides be solid plywood?

[ger21]

Your torsion box beam will be fine.
I'd make the gantry sides torsion boxes as well.

[Biggs427]

How big impact let's say 100mm wide and 40mm tall hole would make?

I can't say but any access hole will make the part less rigid.

[hautamak]

One more question before I can start building, Is it okay to attach sbr 20 to base with wood screws?

[routalot]

I can't see any problem with using wood screws,but they do need to be inserted into correctly drilled holes.I also hope you know the difference between wood screws and self tapping screws and why one or other should be used in any particular application.Strength shouldn't be an issue and if you would like to know more on the topic,quite a few years ago Ed McClave did some very valuable primary research into the force needed to pull a screw out of various types of wood.He published some of it in Woodenboat magazine-where the readership have an interest in this sort of thing-and the factors that are significant are screw gauge,length of thread engagement and wood density.There may be some of his conclusions online.

[fretman_2]

On my MDF build, I screwed the wood screw in, then backed it all the way out, then wicked in water thin superglue to solidify the threads, Then I screwed the wood screw back in. Super strong hold doing it that way.

[wizard]

One more question before I can start building, Is it okay to attach sbr 20 to base with wood screws?

Shouldn't be a problem if they have plenty of engagement. For projects around the house I use a lot of "construction" and "deck" screws. In the case of construction screws, GRK R4 series or their RSS series for heavier work (there are many brands, I just prefer to avoid changing vendors constantly). For deck screws I'm more flexible and generally buy the screws rated for treated lumber that way I always have the right screw on hand.

The trick though with screws is that engagement. You will want to uses screws that have threads right up to the head and avoid clean shanked screws or screws with additional features on the clean shank. If the substrate is too thing if might be advisable to have backer boards of some sort to increase the screw engagement. You probably also know that plywood can split when screws are driven in, that means that even self tapping screws can benefit from pilot holes depending upon plywood orientation.

[routalot]

On this topic I disagree with wizard regarding plain shank screws.I would say they are the best option for lateral location as the plain shank is much less likely to wear local grooves in the soft alloy of the SBR20 rails than the much smaller contact area of other types of screw and the absolute worst type of screw would be the type of deck screw that has the upper portion of the shank reduced to the root diameter of the thread.Do not be concerned if you have to drill a short depth of shank clearance hole into the woodwork as it gives you a very useful start for a pilot drill and a pilot hole is a very good idea.You are trying for an accurately located hole of the correct size to achieve a very positive grip and as such the carpenter's approach to driving the maximum number of screws in a day isn't really a consideration.Maybe you should try a few test holes in an offcut of the plywood to determine the correct sizes and torques.

[hautamak]

Thanks for input, I have now started the build. Base is done and base stands, also gantry parts are now done. Next step is to mill z-plates. I have made all plywood parts with torsion box style and pressed them with hydraulic veneer press. Now I was thinking of routing the base, and gantry parts surface flat with our schools cnc. Would it be necessary?

[hautamak]

Now the machine is ready, only wiring need to be done. However I have problem with my BoB as it doesn't recognize any input. If i set mach 3 options to active low it will continuously hit limit switch. Without active low the inputs are dead.

The BoB have inputs on port 3 and with port 2 it don't give any input even with active low.

I have wire from ground to switch and there to input 2.

I have like the cheapest controller I found

https://www.ebay.com/itm/1x-CNC-USB-....c100005.m1851

[ger21]

I have like the cheapest controller I found

That might be the problem.

Are you sure you have Mach3 configured correctly for that board?

[hautamak]

Yes, I have learned from that. If only...

But yeah stepper motors works fine, only inputs are not working. Maybe I'll try something different plugin for that card.

would this controller be good if I can't get that crappy one to run?

https://www.ebay.com/itm/NVEM-6-Axis...wAAOSwtVxaJhwK

[ger21]

I consider all Chinese controllers to be crappy....

[OlfCNC]

I have like the cheapest controller I found

That's wrong. That is the most expensive controller when your machine starts to create garbage because of the cheap controller.

[wmgeorge]

Yes, I have learned from that. If only...

But yeah stepper motors works fine, only inputs are not working. Maybe I'll try something different plugin for that card.

would this controller be good if I can't get that crappy one to run?

https://www.ebay.com/itm/NVEM-6-Axis...wAAOSwtVxaJhwK

Buy one from a USA Vender, why mess around with junk??

You can call these folks and ask questions before you buy. https://www.automationtechnologiesinc.com

[routalot]

Do we have any reason to suppose the OP is based in the USA? It might be a good deal easier for him to buy in a convenient location.I would have thought it highly likely that he has a configuration problem rather than a faulty board.It could even be a problem between the computer and the board.Can you check the current arriving at the board in any way?I'm no Mach 3 expert but I suspect that there may be a particular mode of installation for getting Mach 3 to work with usb.

[hautamak]

Well, I had not read wiring instructions correctly. BoB need 24v input voltage to get output and input work..

I really don't know which BoB would be good. I live in Finland so there is not much where to pick from. Is gecko controllers good?