New CNC Mill on the horizon

[fvfdrums]

Updated spec after current discussions:

1200x900 footprint area with approx 1000 x 800 cutting area
80x40x4mm steel box section frame with adjustable bed
Aluminium gantry made from a combination of 20mm/15mm plate either standard 6082 or ecocast for the bearing and guide plates
20mm Profile rail on x,y,z
**16/10 on x axis (running 2:1)**
16/10 on y axis
16/05 on z axis
250mm cutting depth on z
2.2kw chinese spindle

electronics (just ideas at the moment)

1 x nema 34 7.7nm running 2 x axis ball screws via a timing belt running dual 16/10 screws
1 x nema 23 3.1nm running y axis on 16/10 screw
1 x nema 23 3.1nm running y axis on 16/05 screw for better resolution

80v Leadshine Drives

75v PSU

Mach 3

How is this all sounding? are we on the right track :)

Design wise the gantry design is very similar to the one Jazz has posted on here before with interlocking aluminium plates (copying someones idea is the best form of flattery right? or is that plagiarism :P) anyway it looks an extremely solid design and I tend to make things over engineered so figured this was a good place to start.

With the y axis I was considering a direct drive using a coupler, all the other drives will use a belt to transmit motion, would it better to engineer it so the motors are all belt driven or would this make no odds?

[JAZZCNC]

**16/10 on x axis (running 2:1)**

1 x nema 34 7.7nm running 2 x axis ball screws via a timing belt running dual 16/10 screws

This contradicts the other.? If using 10mm pitch you won't need any ratio with 7.7Nm 34 and belt drive 1:1 will be fine.

With the y axis I was considering a direct drive using a coupler, all the other drives will use a belt to transmit motion, would it better to engineer it so the motors are all belt driven or would this make no odds?

No don't direct drive keep the belts for resonance reasons even thou your planning using very good drives which handle resonance fantastic. If your copying the gantry I think then I've actually changed the design slightly and the Motor is now on the inside connected to screw with belt. It's very neat and compact. (code for F@#% tight fit.!!)

[PAULRO]

Hi FVFDRUMS, i have been watching this build log because i,m going to build a m/c similar to yours, similar cutting area with similar size tooling(20mm linear guides and 16mm ball screws) .the lengths will be different sizes. i plan to m/c hardwood ( the occasional guitar body) can you let me know where you bought the slides, ball screws and bearing blocks to suit? also is there a download of the specs available so i can incorporate this info in to my dwg.
By the way, how is your build going?

[MikeyC38]

Hi FVFDRUMS, i have been watching this build log because i,m going to build a m/c similar to yours, similar cutting area with similar size tooling(20mm linear guides and 16mm ball screws) .the lengths will be different sizes. i plan to m/c hardwood ( the occasional guitar body) can you let me know where you bought the slides, ball screws and bearing blocks to suit? also is there a download of the specs available so i can incorporate this info in to my dwg.
By the way, how is your build going?

Hi PauRO

I got my parts from Chai at linearbearings2008 on eBay. Many on this forum have used him with good results. I got the following (see link) but swapped the supported round 1100mm SBR16 slides for SBR20. Chai was excellent in changing the order and I received everything intact within 10 days. 3 SBR16 sets +3 ballscrews RM1605+3BK/BF12 +3 couplers | eBay . I'm building my CNC to make guitar bodies

Regards
Mike

[fvfdrums]

Well its been quite a while (9months) since I was last on this thread talking about the machine I was about to start and as per usual a whole load of "Life" has got in the way preventing this from moving forward in the way I had hoped.

Anyway to cut a long story short its got to the time of the year when for me work goes a bit quiet and means I can legitimately take some "time off " a real rare thing, so I have now planned in for work to start on the machine in the 1st or 2nd week of November.

I now have a great garage space I have converted with heating and all my machine tools so it will be much easier to produce a better quality machine in the space.

Only problem is somehow in the last 9 months the folder containing all my drawings has vanished and apparently its nothing to do with the other half :| so I need to start drawing up from scratch again which will give me an oppertunity to have a look at the design with fresh eyes. Honestly I am not sure I will change too much from before as it was based on a machine Jazz had shown me some photos of and I really liked the compact aspect of it and the moveable bed design.

So I guess its a case of watch this space over the next month and hopefully I will be back up and running with a shopping list a workable design to go with it. Thanks to everyone so far for their inputs and guiding me in the right direction.

[fvfdrums]

Quick question that I was trying to get answered earlier in the year but never got a definative so I thought I would get "paint" involved.

I was wondering if the BK12 bearing units have a rubber seal in them before the 2 bearings in the houseing and if so does the machined end of the ballscrew stop at this seal or the black part at the back of the unit or doe it fit right up to the bearings inside the unit. Picture attached is it A or B or even C and I am way off!

On a separate note I am awaiting the arrival of some profile rail and bearing carraiges, managed to find a good deal in the end and they are now in the country according to Royal Mail and out for delivery so there is a chance they may turn up today which would be great.

[Clive S]

If I am not mistaken it is more like B but there is a little spacer at each end of the bearing so that the ball screw does not squash the rubber seals. Be in mind that you will have a bit of free movement at the BF end as the bearing can float in it, say about 3mm. ..Clive

[Jonathan]

If I am not mistaken

You're not mistaken :)