Ordered almost everything for the basic build. The second Gantry will have to wait until I get the first going. The store was short 1 Stepper Motor and I'm going to have to wait for the lead screw nut.

BTW, Mark, what leadscrew did you use?

 

The screw down the inside of the v-slot rail is brillant! I am so stealing that idea for a project!

Needs more video of Routy in operation!

 

It is a little unclear from the pictures. And we have yet to see any video. Are you running 2 steppers off one channel of the grblshield?

 

Well get on it! We want more info!

Understandable, holidays throw a spanner into alot of things. My cnc router has been offline since thanksgiving because I haven't had time to work on it, and its been so cold out.

 

I have been thinking about this Dual Y motor operation for some time. It's ok as an idea but I am not keen on running two motors from one driver. A potential solution would be to replace the Y Motor with a double shafted motor with much higher Torque and then attach a center rod to the inner side with a pulley on the other end to attach to the other drive side of the machine.

I have attached a video showing one idea but it may also be feasible to adapt the design to centralize the motor and have smaller rods coming off either end so that the pulleys were both on the ends of the rods so disengaged from the motor all together. Either way this would potentially reduce the inherent racking problem and 'load' of two motors on one driver.

I hope this invites discussion.

 

Colin that is done in many professional CNC machines. It has advantages and some disadvantages. The biggest disadvantage is the shaft can twist a tiny bit, solution just use a bigger shaft, perferably a hollow tube actually to reduce mass. The normal operation is to centrally mount the stepper/servo on the gantry when doing this. Easy to do.

The advantage is 1 stepper. And they are always synced up.

Now the dual stepper does have an big advantage if used with a 4-axis controller. You can use 2 home switches one on each side of the gantry, when the system homes it homes both y-axis motors and using good switchs can autosquare the gantry. If I build a OX style cnc router, I will probably use the Xylotex 4-axis kit to take advantage ot this.

 

Yes, I can see that the shaft may twist on heavy use, especially metal machining but the Routy CNC is suited to light CNC work, maybe some thin aluminium or brass work but I doubt hard metals could be machined using this machine (I am hoping to be proven wrong) so the center shaft may be a better idea. I like the idea of 4 axis, and that would have been my first choice coming from a CNC background as that is why I don't like the idea of two motors on one stepper driver but the 4 axis again means an extra motor, and an extra axis board which all add to the cost. The center shaft and single Y Motor proposal may reduce the overall cost a little which for those wishing to utilize the small machines as a starter machine is a bonus. I intend to find a center rod and give this a test run in the New Year.

The OX will be capable of heavier work so I would definitely recommend 4 axis on that.

 

I have been looking into it heavily. The arduino style control with 4 steppers is barely cheaper then the Xylotex full blown hobbyist CNC board, with 4 motors and PSU.

http://xylotex.netfirms.com/OSCommerce/catalog/product_info.php?cPath=26&products_id=40

Get some hardened drill rod, or build up a torsion tube using steel, or alminum tubing of the appropriate ID, and shaft of the correct ID for your pulleys. Glue the shaft into the tube and you would have a very stiff for its weight drive shaft.

 

Anyone start a build yet? I've got everything except timing belt, and a leadscrew nut. I think I'll attempt to construct my own out of delrin. Just have to finish a project for my wife first

 

I have started, but like you I haven't got the leadscrew sorted yet. Have already noticed that the parts list ought to have some double t nuts on it instead of some 2 hole joining plates. Have used single t nuts for the moment, but they aren't as good. The 2hole joining plate is a bit thick, and would need longer screws. I am impressed with the solidness of the y gantries plates I have put together.

I am also using the cnc shield from http://blog.protoneer.co.nz which gives you a driver for all 4 axes. It does require soldering though. Looks like a good solution for budget users.

 

Good tip on the Protoneer Chris!

 

Just be aware that the Prontoneer does not support true 4-axis without custom firmware. Grbl that is designed to work with only supports 3-axis and the prontoneer just electrically slaves the 4-th axis to X,Y, or Z. This is still an improvement over useing the grblshield and just connecting 2 motors to one driver. as you can then drive both motors at full power. Another advantage of the Prontoneer is using replaceable stepper drivers. If you blow one up, you can just swap it out, instead of the entire board.

 

Sorry if I didn't make that clear. I was speaking in reference to this build, for which it is fine. I would also recommend getting the drv8825 drivers as they can handle more amps for not a lot more money.

 

Hey Mark, this is really nice work. I'm planning on doing a slightly different (but derivative!) version in Inventor, will share when it makes sense.

I do have a few questions:

1. What's the purpose of the smaller rail on the gantry (the 20x40)? It appears to be fastened only by one screw at each end, I'm not seeing how it contributes much to system stiffness. I thought it might be there just to support the electronics and cabling, is that it?
2. I see that you have dual V-slot gantry plates. Is this needed for stiffness of the rollers, for motor mounting, or both? I'm also wondering how you sorted out the eccentric bushings for the gantry carriage -- do you leave the back plate loose while you adjust, then tighten once the rollers are set?
3. Do you find getting the two long rails parallel and lined up with the rollers a fussy process?

Thanks and regards
Neil

 

I'm building this. Will it hold a an 8lb heavy duty router/spindle or does it have to be the lighter dremel tool?

 

tbh I would go with the Ox if you are looking to pack that sort of hardware, I would suggest up to 1kg for the spindle on this particular machine.

 

Have you given any thought, or figured out if it would even work, if you replaced the 2 motors on the X axis with a double shaft motor and an extension rod to the other side?

I'm always concerned about tuning and sync issues when using a slave motor.

 

Just purchased everything except the lead screw nut, 4 steppers, and the m3 cap head screws (45mm). Wish those weren't out

Looking forward to building this puppy, and I'm sure I'm going to have plenty of questions. Any recommendations for a router OR max weight of the router?

 

Alright, so... can you provide links to the things that definitely worked? Much appreciated!

 

I've been researching this and someone said 1kg max for the router. So I am going to try to use a remote control airplane brushless DC motor refitted with a spindle and possibly a cooling system. One other person has used this before and said it does everything up to and including 3/8" aluminum plates. The weight is about 200g so with the spindle and fans it will easily be under 1kg. It's basically like getting a 1kW spindle with 0.015mm runout which would cost maybe $400 but instead is only $100 or less.
http://www.ebay.ca/itm/171124328079

http://www.ebay.ca/itm/151202933572

 

That's not a bad idea. I have a decent-sized cheap router that is probably too big. I also have a smaller rotozip that might be borderline. Will know soon if it works hehe