I've built this machine 100 different times in my head!!!

[JAZZCNC]

Like jonathan it's nice to see someone who's actually done the leg work and payed attention. . 10/10. . Big respect. .

Agree with Jonathan on every thing he's said except not using the Ecocast.! Even thou you will machine the bearing mounts etc unless you surface and make parallel both surfaces your still going to have troubles and in-accurecy. The problem comes from the cheaper plate not being uniform thickness so you can't be sure it's the same thickness (Or flat) all along it's length. This means buying much thicker than needed so it can be surfaced and still have the required thickness to be strong.
I used to do just this but since the Ecocast has been easily available in small qty then I don't bother any more and it cuts out some of the work involved and makes things that bit easier.

To be honest the 20mm plate is still fine regards strength even with the neccesary slots cut, I've made several with 19mm 6082 and slots etc and they are more than strong enough for even the most demanding jobs.! (Within reason) See pics of what you may have seen before just not striped down like these.?
(obviously more thickness will be stronger but not 20mm gets the job done.!!)

The only other point I will mention is the belt setup and the lack of protection from chips etc.!!
You probably know my machine use's this setup and I'm guilty of not covering the belts and while it's never been a problem, other than grabbing my teashirt a few times and trying to eat me, I would still advise you to cover them up before using the machine.! . . .I'm pretty sure the constant pounding from chips etc has or will shorten the belts life so worth doing before using the machine otherwise like me you'll never do it after machines put to work.!!

Anyway great work and can't wait to see it turn into reality. . .

[Iwant1]

Redrawn the z axis with new 25mm plates for the rear and front. Also included registers for the NSK rails and slides although they are only 1mm. It is a very tight fit and looks much sleeker now at only 64mm depth. I suppose If I had to then I could sink the bk/bf blocks a few mm into the rear plate, just where the blocks go. Its not easy to show but the ball nut's flange head sticks into the front plate by a few mm, which could be a good thing if the hole is machined accurately.

The spindle cutter head has now moved 30mm towards the y axis and now rests between the x axis bearing blocks. Pictures showing the new design and also how far the z extension could be dropped. Its around 250mm, not that I would need that much, but the rails are long so might as well use them. I try to put as many detailed pics up for all novices to see, as this is what I was looking for while doing my research. Hope it helps someone.

Adil

[JAZZCNC]

Ermm.!! . . . . Been looking at this thinking don't seem quite right.??? . . . I'm sure it's correct because you've obviously taken lots of time over it but I'll ask anyway just in case.!!

The bearing/rail height seems low.? from the dimensions on the drawing it appears to be about 16mm this is very low even for 15mm profiled rails and surely can't be right.? Do you have the bearings set in pockets.?

[Iwant1]

Thanks for noticing how small my profiled rails are. I mentioned earlier in the thread I didn't realise that they came in such low profile dimension. I got them for £70 from ebay for two slides and 4 rails as 15mm width and 550mm length. I've attached some pics to show their dimensions with respect to the bk/bf blocks. This is why I'm in a pickle over using 25mm plates for the z axis with 15mm machines out from each.

Do you think I should sell them on and get slightly larger rails.

[WandrinAndy]

I've attached some pics to show their dimensions with respect to the bk/bf blocks.

As a novice who has never seen any of these components in the flesh so to speak, those dimensioned pics have really helped me and reminded me that I need to get a digital caliper... thanks Iwant1... I'm following your build with interest btw, and want one too!

[JAZZCNC]

Do you think I should sell them on and get slightly larger rails.

I wouldn't go that far but they certainly are not ideal in the respect they make the pockets deep.!!

There is one thing I'm not to sure about and it's hard to tell from the pics, is that they don't look like the 4 row type bearings.? This makes them that bit less ideal and less able to stand the strain that a Z axis will come under.!! If 2 row type then I think for a Z axis then yes I'd sell them and get 4 row type more suited and making the job a bit easier.!!

[Jonathan]

Having 4-row profile rails is an advantage over 2-row - twice the balls = twice the surface area in contact with the rails which should get better stiffness, in addition to factors usually mentioned. However 2-row is still in a different league compared to round rails, so unless you can sell them and get better rails for the same price I think there's other places the money would be better spent on. You've got long rails, so use that to your advantage as if you're prepared to sacrifice some travel you can space the bearing blocks out more to reduce the load on each, so long as the piece they are mounted on is stiff. I got 760mm rails for my Z-axis, so if I ever get round to making it I'll keep 400mm travel and have the bearings 360mm between ends, which is slightly extreme but the rails were cheap so why not.

Lost of cnc machine parts are available in the SketchUp marketplace, which you get to from within SketchUp. All the rails, bearings, spindle, motors, ball nuts, etc are available.

The standard part libraries can be helpful, but I tend to draw things myself so I can be confident it is correct. I guess if I used SketchUp I might think differently.

[Iwant1]

The standard part libraries can be helpful, but I tend to draw things myself so I can be confident it is correct. I guess if I used SketchUp I might think differently.

Very true, many of the parts I used, such as the pulleys, timing belts, ball nuts, linear rails and slides were all over 50 times the size I needed and some not 100% right. I spent loads of time scaling the items as a whole and also separately in each axis so that they match what I had. The problem was in SketchUp, the scale function works as a percentage where as I wanted dimensions, so I had to resize, measure, resize again, measure again..... to fractions of mm's. Next time I'll make them up but then I suppose the same tedious task will be spent with my vernier calipers.

Regards the profiled rails, I think what I paid for these 'mini slides' was very good and I definitely won't be able to get larger ones for this price. I spent ages today trawling eBay for profile rails and carriages and found that I can get Thk and Nsk sets at similar length for around £150 with p&p. Problem is I had to constantly go to their manufacturer websites and check whether they got 2 or 4 rows of balls. Then you find out the balls also have 30,45, and 90 degree configurations. Plus I started mixing models like hgh, hgw, hsr, ssr, sr, lf, lu with the wrong manufactures.

I've seen Zapp is very reasonable with his Hiwin rails and carriages, which work out at £180 for a brand new set, hgh15ca and 500 rails, compared to £150 for similar spec second hand Thk/Nsk on eBay. I don't understand how there can only be £30 difference, are Hiwin a cheap brand compared to Thk and Nsk.

I'm also not sure what preload is suitable for my z axis, as gravity is always going to pull the carriages down especially when all components are connected to it. Does ZO, little preload, mean there is more play between rail and carriages then ZA, medium preload. I have no actual experience what any type of preload feels like, as I only have the second hand ones to go by, which you can blow from one side to the other.

Thanks
Adil

[Iwant1]

I'm trying to make the build as strong as I can or will ever need. There's no specific need for this router, just for fun. Many of my mates ask, 'what's the first thing you're going to make?' I tell them a plaque saying 'test cut', lol. There's no budget to it, just being wise with money. In the end I'm sure it will cost near £1500 once spindle, plate ali, steel tubing, pulleys and belts are factored in. So far Chai took £550 and Zapp took £250 for the electrics.

Time is always a problem as the family want some dad time in the evenings after work. Suppose I'll have to get my 2 and 4 year olds to help mix up my screws and loose my tools. Funny how all kids love work shops, so many things to play with.

Adil