Building a Routermate

[tigger_na]

Dear Forumites

I am building my 6’x10’ Torchmate Routermate table and water table. I’d like to share the progress during the build process, to invite critical comment and share my experiences. First the hardware:

* 6’x10’ Torchmate Routermate kit, for a final safe travel of 3,050x1,710x75mm as measured
* Hypertherm Powermax 1650 plasma cutter with Duramax MRT 50’ mechanized torch
* Accessories: Blue screen AVHC, Hypertherm 023206 interface cable, Torchmate 4 & Bobcad software, TM laser crosshairs, 6' wide dual tool mount, pipe cutter attachment, TMX limit switch kit, Harris 3-Hose oxy-acetylene cutting outfit and plate marker.

The plan is to end up with the most versatile CNC table I can afford, able to cut plate and structural steel on the table and pipes and square/rectangular stock on the tube cutter, route plastic and aluminium and engrave. I’m a bit out of the centres of civilization, so many hardware choices I implement will often be dictated by availability, not functionality.

Welcome, and hopefully you enjoy yourself as much as I do.

[North Shore Fab]

how are you going to cut square stock?

[tigger_na]

The gantry has to move up and down on the water table to accommodate high work-pieces. I chose bigger-than-recommended (75x75 SHS) steel for improved stability and settled on 120x80x5 RHS.

As usual the stock lengths were not straight, with a deviation of 5mm over 4m. Even after straightening them with transverse welding runs they remained 2mm out-of-straight. This forced me to raise the rails off the steel and fill the gap with metal filler compound. I used Diamant Multimetall manufactured by DIAMANT Metallplastic GmbH in Germany for its superior strength, temperature stability and ability to flow into gaps as small as 1mm. Expensive but worth it (And don't even dare asking your wife or mother to clean your clothes after you worked with this).

The rails were prepared with a grub screw between the hold-down screws to adjust the height and level and spring pins to locate the plates after grouting. Since I needed to adjust the width between the rails (and because I’m unable to tap a straight hole), I relieved the original holes with a straight die grinder. The underside of the rail and top of the steel was cut with an angle grinder to provide adhesion surface for the grout. Be careful when handling the rails: They may be hardened but are still soft as butter and attract gremlins with little hammers when you’re not looking.

The height of the rail was adjusted with a dumpy level to within 0.1mm, and the level to 1mm/m. The grub-screw in the middle was very helpful to adjust the transverse level: The rail swivels around it and minute adjustments can be made. The straightness of one rail was done with a fishing line and feeler gauge, the center-to-center spacing between rails was kept in check with key steel tacked to an angle. Final deviation is less than 0.1mm.

The tie between the rails didn’t need to be super strong, so I used light I-beam. Just to be on the safe side the corners were also located with spring-pins. This probably doesn`t do much to keep the rails in square, but every bit counts, even if it’s just good intention.

[tigger_na]

Originally Posted by North Shore Fab

how are you going to cut square stock?

The plan (as opposed to how I'm actually going to it, if ever) is to use some sort of round attachment where one feeds the square stock through. Think a barrel that runs on the table rollers, with the square stock running through it's middle. I'm still stressing whether the cutting software will be able to handle it, but will cross the bridge when I come to it.

[tigger_na]

The gear rack received similar treatment. I couldn't bolt the gear rack directly to the frame, as the deviation from straight is about 3mm on my steel. The fact that I used 120x80mm RHS instead of the recommended 3x3”, plus the gap between the steel and rail of at least 2mm means that the stepper motors have to stand 3mm proud of the motor mount. Once I get the table running its going to cut the necessary spacers.

The gear rack was re-drilled in-between the factory holes, to provide more support during the adjustment. Two grub screws were added to each mounting bolt for level and depth adjustment, but this time around I omitted the hollow pins. The grout would (and did) fill the gap between the bolt and the mounting holes, providing positive and permanent location of the gear rack.

There is an advantage to not having the gear rack flush on the steel: The gear on the stepper can engage the full width of the rack without fear of catching the face of the gear on the support steel. Still I had to cut the stepper axle shorter with a millimetre to be sure. The vertical distance between rack and rail was set with two 20mm key steels tacked together, for a total of 40mm. The result? Less than 0.1mm deviation, I reckon.

A downside of this arrangement is that the bolts used to hold down the rack (M6 cap screws in an 8mm hole) is that the head will catch on the stepper mounting bolts. I reckoned that, since I can't adjust the rail after grouting and it was as accurate as I was ever going to get it, it would be easiest to cut off the head of the cap screw, leaving a nominal 1mm for holding the rack.

[North Shore Fab]

too lazy to read everything right now, that picture with the spur and rack, is that the gear box or motor? if you are going straight from the motor to spur i dont think you will have enough power to route.

[tigger_na]

That is the gearbox. I think I have very little power nevertheless, I can't get the gantry to accelerate properly without losing steps, but since the gantry rails aren't fixed to the table yet I've settled on low acceleration settings until I get the table nice and sturdy.

The gearbox is 1:10 and the stepper motors are marked "MP-2303-S-6, 3V 6A 0.5mH". I'm running them with the settings for a "TM 8A Pro Series Micro Stepper (6501-x-080-m)".