Hi Gary the machine is from Strike CNC.Quote:
Originally Posted by Gary
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Hi Gary the machine is from Strike CNC.Quote:
Originally Posted by Gary
The motors are nema 24 and to get anything useful from them you will need to have quite a high voltage power supply.
Also the comment that they are two small for 25mm diameter ballscrews is totally right especially if you want to get them spinning fast.
The 4Nm is just the holding torque and totally irrelevant, and without a high voltage these motors will perform really bad.
I was going to post something similar to what Jazz has just posted about this machine, but there's no point now as he's said it all really.
Hopefully the 4nm motors are these:
http://www.cnc4you.co.uk/index.php?r...&product_id=70
So strictly speaking Nema 24. They're quite promising as they have a low inductance for their size, though I've never tried them. It's such a mismatched system. Instead of going for a higher lead ballscrew for X (i.e. RM1610 like they used on Y, or RM2010) to prevent whipping they've used a 25mm ballscrew then stuck bigger motors on to try and compensate, but it will still be nowhere near the performance (especially acceleration) you could get with 3Nm motors and a smaller diameter screw. 5m/min is adequate as the machine probably isn't rigid enough to cut faster than that.
£600 sounds a lot to add for an enclosure, though the price is understandable given the use of aluminium extrusion. Why not just make it out of wood, e.g pine or if they have a big enough machine cut the enclosure out of plywood sheet? Should be much cheaper.
You could add more braces to the bed parallel to the X-axis without interfering with the ball-screws. Without that you may see the bed bend away from the tool when it plunges down. Plunging with the tool something to avoid anyway (unless it's a drill!) but not always possible.
What's with the Nema 24's My understanding is that the size is determined by the across the frame distance so 2.3" and as they all have to fit the same bolt hole pattern they should all be the same. I have bought these larger powered 4nm's from Zapp, Roy at DIY - CNC and also from the link above and China direct. They are all interchangeable so all must be 23's unless i'm missing something here ?
Also £600 for the enclosure doesn't sound high to me. These guys are working for a living, not pissing about in a garden shed and that stuff isn't cheap. I built two enclosures for the KX series machines to go in at the shows for ARC. I'll bet he wished I'd only charged him £600 quid a pop :tongue:
Attachment 5358
To tell you the truth I think they made a mistake on the enclosure as I know that the extrusion was over £400.00 for my frame work alone
James
I can't see the 4nm motors at Zapp, only the standard 3nm that everyone sells.Quote:
Originally Posted by John S
What I meant is I'd never recommend paying that much for an enclosure when it's something anyone can make. You don't really need to know anything about CNC to make an enclosure, as it's just a box. Plus if you're going to charge £600 for an enclosure why make it from extrusion when you get a bigger profit with other materials :lol:Quote:
Originally Posted by John S
Nema 23 motors are 56mm square.
the 60mm motors are an oddball so they called them nema 24.
We only sell the 3nm version of the 60mm motor, i tested the higher torque version and found that they performed worse than the 3nm version.
As john rightly says, you cant expect a company to make a bespoke enclosure for near nothing, £600 is not bad, we all need to make a living.
I suspect these are nema24 and I incorrectly called them nema28. Everything else seems to fit.
What does concern me is the points raised by some about the inertia and general mass of the screws being too much for the stepper motors. Obviously its hard to tell without testing and you can be sure I'll post some video's of the machine working to allow you to look for any issues that I might not be able to identify being a beginner.
Supposing I do find that the motors are inadequate, how big of a job would it be to upgrade them to something suitable?
Where there's clear panels, they've used Lexan too rather than just clear perspex. I've had a quick look at prices for a 4 x 8ft sheet and its not cheap. The machine is 1.8m D x 1.8m W so your looking at a couple of sheets of that if you arrange your cuts sensibly. Overall I was happy at £600.Quote:
Originally Posted by Gary
I know what you guys are saying though. I DIY too (not CNC machine though) and don't consider my time spent as a commodity so £600 for a cover would seem expensive compared to something I could knock up. In this case though I wanted a neat package that ran straight out of the box.
Have any of you guys tried building this vacuum hold down kit:
http://www.m-powertools.com/products...h/big-mach.htm
The price seems good compared to the alternatives and because it works off a regular hoover you don't need venturi or vacuum pump.