[Mountaincraft]

Hi, I am planning on embarking on a journey that will eventually lead to my having two CNC tables.. a MechMate router table (4x8) and a hybrid solsylva/mechmate plasma table (4x10)... I have some design questions I need to resolve...

I'm planning on starting with a solsylva router table, and integrating some of the parts into a plasma mechmate (or mechmate/solsylva hybrid) and a mechmate router... 2 separate tables...

So I have a couple questions about options in planning the original solsylva build and what can or can't be done when I decide to move forward from there...

1) I have the option of using aluminum for the gantry and Z carriage on the solsylva.. Is this a problem for plasma? Is the heat from the plasma an issue for the gantry? Would sparks or slag cause any damage to an aluminum gantry or Z carriage?

2) I understand that 'cutting force' is not an issue with plasma, as there is no actual contact between the machine head and the material being cut... Does this therefore allow for smaller steppers? The reason I ask, is that the solsylva specs out 425 in oz NEMA 23 steppers... If I can use these cheaper steppers and their associated drives/power supply, that would make life easier... The plan is to make a mechmate based heavy steel base table, and bolt wooden rails to it, and build the solsylva system on top with an all aluminum gantry... then later, shortening the aluminum gantry, and modifying it to ride on top of the mechmate steel rails and rack system.. (X axis), and replacing the router with a plasma torch... (likely replacing the solsylva bearing system on the gantry with linear motion bearings at that time as well if I'm not happy with the homemade bearing system)

3) The solsylva plans call out for a 2" x 6" x 1/2" aluminum C channel for the gantry beam.. I'm thinking about replacing this with a more expensive T slot aluminum channel (2 x 6 if they make such an animal, otherwise 3 x 6)) ... As this would make 'modifying' the gantry later much easier... But I'm not sure if this weakens or strengthens the gantry beam.. So I'm wondering which is a better gantry material, the extrusion or the C channel? If the open slots are an issue with the extrusion, I could always cut some thin sheet metal to cover exposed/unused channel surfaces...

This plan allows me to get a lighter duty router table up and running, while I build a true to plans mechmate router table, later modifying the lighter duty table to become a hybrid mechmate plasma table...

If I can resolve those three questions, I think I have enough info to gather some materials and start construction of some components..

I also posted these questions over at the MechMate forum...

Thanks for all your advice and help,:cheers:
Mark

[jimcolt]

There are many cnc cutting machines on the market with aluminum gantries....there is very little reflected heat from the process until you get above about 260 Amps. Most air plasma cutters are under 100 Amps.

As far as drives go......plasma works best with acceleration in the 40 miligee range (or better). The majority of plasma cut speeds are under 200 inches per minute, however on very thin sheet materials plasma may require accurate motion at up to 450 inches per minute. Fluid motion is improtant as well....if there is any noticeable "cogging" it will shop up as striations in the cut edge with plasma.

Jim Colt Hypertherm

[Mountaincraft]

There are many cnc cutting machines on the market with aluminum gantries....there is very little reflected heat from the process until you get above about 260 Amps. Most air plasma cutters are under 100 Amps.

As far as drives go......plasma works best with acceleration in the 40 miligee range (or better). The majority of plasma cut speeds are under 200 inches per minute, however on very thin sheet materials plasma may require accurate motion at up to 450 inches per minute. Fluid motion is improtant as well....if there is any noticeable "cogging" it will shop up as striations in the cut edge with plasma.

Jim Colt Hypertherm

Hi Jim, thanks for responding...

Wish I knew more about drivers and steppers, but I don't.. So it's all greek to me... Does this mean that the recommended xylotex 3 axis drive kit will or will not fit the bill? Or will I have to get gecko drives or similar?

Basically, we're looking at a final product that will have a heavy steel base, with v-rails on the longitudinal x axis beams, hardened steel rollers, attached to a steel end plate, with a spring loaded stepper, driven rack and pinion (MechMate system)... The end plates will be attached to an aluminum gantry beam (approx 5' wide) with an all aluminum Z carriage.. The y axis will also be rack and pinion, and the Z axis will likely be Acme screw..... I may use a 1" drive shaft to connect the two X axis pinions, or a second slaved stepper...

Would the Xylotex package be sufficient, or am I gonna need something better?

Solsylva claims 350-485 ipm rapids with the rack and pinion system and the xylotex drivers/steppers..... but gives no data in as far as acceleration and what not...

Thanks again,
Mark

[Mountaincraft]

There are many cnc cutting machines on the market with aluminum gantries....there is very little reflected heat from the process until you get above about 260 Amps. Most air plasma cutters are under 100 Amps.

As far as drives go......plasma works best with acceleration in the 40 miligee range (or better). The majority of plasma cut speeds are under 200 inches per minute, however on very thin sheet materials plasma may require accurate motion at up to 450 inches per minute. Fluid motion is improtant as well....if there is any noticeable "cogging" it will shop up as striations in the cut edge with plasma.

Jim Colt Hypertherm

Hi Jim, thanks for responding...

Wish I knew more about drivers and steppers, but I don't.. So it's all greek to me... Does this mean that the recommended xylotex 3 axis drive kit will or will not fit the bill? Or will I have to get gecko drives or similar?

Basically, we're looking at a final product that will have a heavy steel base, with v-rails on the longitudinal x axis beams, hardened steel rollers, attached to a steel end plate, with a spring loaded stepper, driven rack and pinion (MechMate system)... The end plates will be attached to an aluminum gantry beam (approx 5' wide) with an all aluminum Z carriage.. The y axis will also be rack and pinion, and the Z axis will likely be Acme screw..... I may use a 1" drive shaft to connect the two X axis pinions, or a second slaved stepper...

Would the Xylotex package be sufficient, or am I gonna need something better?

Solsylva claims 350-485 ipm rapids with the rack and pinion system and the xylotex drivers/steppers..... but gives no data in as far as acceleration and what not...

Thanks again,
Mark