Strike CNC (My first CNC router)

**Shinobiwan** · 12-07-2012

OK here's some shots of the problems with Strikes replacement Gantry.

**Shinobiwan** · 12-07-2012

At this point I'm going to re-design the Z plate and then pay someone on here to cut the part.

I don't have many regrets in life but not building my own machine is now one of them.

**Shinobiwan** · 12-07-2012

Btw is it essential to have the ballscrew floating end mount on? The bearing is damaged and I figure it isn't really needed for such a short ballscrew since its supported at the fixed end and the ballnut?

**m_c** · 12-07-2012

Originally Posted by Shinobiwan

Btw is it essential to have the ballscrew floating end mount on? The bearing is damaged and I figure it isn't really needed for such a short ballscrew since its supported at the fixed end and the ballnut?

Probably not.
The support bearings purpose in life is to support long screws from bending under thier own weight, and/or to stop screws from whipping when spun at speed.
If the screw is short enough/not spun fast enough that whipping is going to be an issue, and it's not long enough/mounted in a way it's own weight could bend it (i.e. hung vertically), then you don't need one.

I'm sure Jonathan will be along shortly with the required calcs for working out the theoretical critical/whipping speed (or just search for his posts, as he's covered it before)

**Jonathan** · 12-07-2012

Agree with what m_c said. You can find the formula he suggested by searching for screw critical speed on google, but assuming the ballscrew is 350mm long the critical speed is 3500rpm - so 3500*5=17.5m/min. The formula isn't that accurate, but that's a huge amount more than you'll ever get on the Z-axis so you're fine to run it. It's <£2 for the bearing you need on eBay, so it's not much loss to get a new one, not that you should have to pay for it anyway.

This thread is the first result on Google for 'Strike CNC', so I wonder how long it will be until they re-brand!

I doubt they will go out of business soon, as it's so easy for these companies to blatantly lie about their products:

http://strikecncrouters.com/page2.htm

**Gary** · 12-07-2012

If you want a critical speed calculator, i use this one.
http://www.nookindustries.com/ball/BallCalculators.cfm

**Shinobiwan** · 12-07-2012

Originally Posted by Jonathan

Agree with what m_c said. You can find the formula he suggested by searching for screw critical speed on google, but assuming the ballscrew is 350mm long the critical speed is 3500rpm - so 3500*5=17.5m/min. The formula isn't that accurate, but that's a huge amount more than you'll ever get on the Z-axis so you're fine to run it. It's <£2 for the bearing you need on eBay, so it's not much loss to get a new one, not that you should have to pay for it anyway.

This thread is the first result on Google for 'Strike CNC', so I wonder how long it will be until they re-brand!

I doubt they will go out of business soon, as it's so easy for these companies to blatantly lie about their products:

http://strikecncrouters.com/page2.htm

Not to worry Jonathan. If you lay too many bad eggs eventually it'll make a stink.

I'm not the only unhappy customer

http://www.cnczone.com/forums/europe...nc_please.html

In particular this comment from that customer rings very true:

"On receiving my machine (the eBay service was great!), I found that the build quality was terrible....really terrible. Basically, I have completely rebuilt the machine, adding a host of parts that I made to strengthen and support the various axes. Most of the extrusions and support rails were not bolted correctly and the stepper motor mounts looked like they'd been chewed instead of machined!

However, I found that the price paid was actually not that bad, when used as a basis for a new machine, but you would most definitely need to at leat check the build quality or better still, strip it down completely."