Your Opinion MK2 .. STRIKE CNC machine

[Jonathan]

Why not convert one of the milling machines to CNC, or is the travel insufficient? For the 4th-axis you can just use a Vertex HV6/HV4 (or similar) rotary table and add a stepper motor to it. I guess you might already have a rotary table to do them on the mill.

Most of what I said about the machine you linked to in China also applies to the Strike CNC machines, so I wont repeat it here. They've used Hiwin rails on X/Y, which is of course excellent, but the spacing of the bearing blocks on the longest axis is quite small - only the width of the gantry sides. That gets extra travel, but sacrifices so much potential rigidity. The Z-axis supported round rails (I think?) which could be fine, except not how they've mounted them. It's hard to tell from the photo so lets compare to their other machines:

http://www.ebay.co.uk/itm/4-axis-3D-...ht_1071wt_1270

That one uses profile rails which are by far the strongest type of rail, but they've put the bearing blocks on the Z-axis aluminium plate instead of putting the rails on this plate. If the rails are there then distance between the support (bearing block) and the tool tip is proportional to the axis extension, whereas the way they have it this distance is always the maximum value. Increasing this distance clearly decreases rigidity.

Also it says in their description two motors on the Y-axis, but in the picture it looks like just one motor and ballscrew? Perhaps clarify that the picture is up to date and get some more detailed ones?

The only way you're going to get a good CNC router is to, on order of cost; make it yourself, design it yourself, make what you can and pay someone to cut out parts you need, pay someone who knows what they're doing to make one to your specification. Since you already have a milling machine making one yourself seems like the best option. I just had a similar size mill to you and a micro lathe when I made mine.

[Shinobiwan]

Hey PWD,

I bought a machine from Strike in December last year and had some problems but also a relatively happy ending.

My advice, and this goes for any place you buy a machine not just strike, get it writing when your machine will be ready for delivery that way its clear what the schedule is for all parties involved. Never pay in full, leave a deposit when ordering and pay the remaining balance when the machine is ready to ship out to you. If they're decent they'll be fine with this, if they refuse then consider that they just did you a favour and walk away. Get a specification list and quiz them hard on the real world tolerances/accuracy of the machine, get that info in writing and compare to what the machine actually achieves. If its a way off the specs then go back and tell them its not good enough. Lastly, if you don't know enough about what your buying then speak to someone who does and do this before you buy. It'll help you avoid wasting money on something that isn't fit for purpose.

I didn't follow these guidelines when I bought but if I had then I doubt I'd have had any problems.

[Shinobiwan]

Most of what I said about the machine you linked to in China also applies to the Strike CNC machines, so I wont repeat it here. They've used Hiwin rails on X/Y, which is of course excellent, but the spacing of the bearing blocks on the longest axis is quite small - only the width of the gantry sides. That gets extra travel, but sacrifices so much potential rigidity. The Z-axis supported round rails (I think?) which could be fine, except not how they've mounted them. It's hard to tell from the photo so lets compare to their other machines:

http://www.ebay.co.uk/itm/4-axis-3D-...ht_1071wt_1270

That one uses profile rails which are by far the strongest type of rail, but they've put the bearing blocks on the Z-axis aluminium plate instead of putting the rails on this plate. If the rails are there then distance between the support (bearing block) and the tool tip is proportional to the axis extension, whereas the way they have it this distance is always the maximum value. Increasing this distance clearly decreases rigidity.

When buying from Strike you have to know a bit about what your ordering. Just taking their 'stock' machine might end in disappointment as corners have been cut to meet a price point. Virtually every aspect of the machine is configurable and this is where you have to do your home work and tell them what you want. Of course that means the price goes up too. If you want to flip around the rails and blocks for the Z axis then you have to tell them to build it like that. Same goes for the gantry uprights, ask for larger extrusion to widen the bearing block spacing.