[santiniuk]

Hello folks,

After a year to the exact day, tonight I start my CNC MKII build.

My original thread which kicked off my interest in homemade CNC's is

http://www.cnczone.com/forums/showthread.php?t=7286

(Final picture of MK I in its new home in the garage attached.)

Through this build log I rambled on and on but had some great encouragement and advise from people around the world. I knew nothing about CNC's but I had the urge to build one.
It's true to say I have made some good mates through this very forum.

The MKI CNC was built almost entirely from bits I salvaged, scrounged & bribed people for. It's still in use and never fails to impress my geeky friends when they visit. Some just thing I'm mad !
The restriction of this machine was table area. It didn't take long before I was drooling at Benny's (YNNEB) machine as the table size allowed so much scope for bigger and better things to be cut.

There are many other great designs on here I hope to incorporate in mine.

It was obvious that this machine would not be built skipratting and I would have to pay for the component's.

Finally after a long time I now have enough bit's to kick off some ideas for MK II.

The Table area will be approx 1.5m * 1.5m, more than enough cutting area for my needs. At last enough area to cut my holy grail. A guitar body !

At this stage I have an open mind on the build design. The only concept I would like to pursue is to make the CNC retractrable into my garage rough space. I have some thoughts on this and will investigate further in the build but ideally I don't want the machine hogging 1.5m*1.5m of my treasured garage floor.

I really would like the members on here to post any pictures, designs etc that you think my components listed in the posts below would be suitable for.

The electronics for the machine will be Picstep 4, and the same motors as MK I. The software is Mach III.

Enough rambling, some pictures of the main bits I have for the build.

[santiniuk]

These items I searched ebay daily for.

It's a long story but I ended up with 5 THK 1480mm long and 6 SSR20 carriages. I may have another two SSR20 carriages available. (Certainly 1).

They are the business !

[santiniuk]

2 long Ballscrews & Nut, complete with NP15 bearings.

Model THK BLK2020-3.6ZZ

Length 1460mm

20mm diameter

[santiniuk]

These two ballscrews I did actually salvage. They are new and should be ok for a Z-axis.

Larger one is 525mm long

Shorter one is 280mm long

[santiniuk]

Believe it or not I was given these last week from a work colleague.

They are 2 * 520mm NSK rails with 4 LSR15 carriages.

The longer pair is as above but 700mm long.

I plan to use these on the Z axis.

[santiniuk]

Finally,

Testing in the kitchen. Do you think the wife would let me leave it there ?

[JavaDog]

Ah man, you'll manage to build two machines in the time it has taken me to get one not even finished. I've really got to get my arse in gear.

That being said, judging by the parts so far - you are really going to out-do yourself!

[Mike F]

Santiniuk,

Youv'e certainly come up trumps with the linear guides and blocks. Did you find these on the UK eBay or US? I had no joy at all looking for parts in the UK this time last year. I appreciate some were donated by a work colleage - look after that guy, there may be more to come

I am interested in your idea for the retracting table and look forward to seeing some drawings/3D modelling.

Now, if only I could getto finish my first machine.

Mike

[MrBean]

Spooooky. A year to the day.....
Looks like you've got some cracking parts to start your build.
Now that you've finally started a "build log", we want no slacking, plenty of CAD and progress updates.

I've not visited here as much as I'd like just lately, but I'm going to make sure I pop in regularly to see that you're not slacking.

I think I'm getting that urge to do something myself...........

Regards Terry.

[Pat2000]

Santini, nice bits o steel!! I have simular ambitions as per your m/c but I'm trying to do it on a 'shoe- string' so my linears are round bar stock - supported and I'm toying with using Delrin for bearings/split bushes.

what motors did you use? and did you get them in the UK?

[santiniuk]

Java,

Your underwater project is too much of a disstraction. It is a good one however and was a great thread on here. Now get your tools back into action !

Mike,

Your thread was possibly the one that made me think about alternative designs and ways to minimise floor space requirements. It looks like the school work is a heavy load. I do look forward to seeing the machine in action however.

The parts are all bits from ebay U.K, they have been quite rare. To be honest a lot of items are listed with strange names. So hunting was the key.

The Cad work will start shortly, I'm still investigating the retracting table options. I was thinking about legs that fold inwards. i.e B&D workmate type of concept. Obviously much stronger and with locking pins.

Mr Bean,

Your spending too much time in Helicopter world. Get yourself back into the CNC scene !

Pat,

The motors are from RS components. part number 440-470. They are 2.5V - 2200 mNm. I'm sure with the right design round linears and Delrin will be fine. Do you have a build log ?

Cheers,

[Pat2000]

Pat,

The motors are from RS components. part number 440-470. They are 2.5V - 2200 mNm. I'm sure with the right design round linears and Delrin will be fine. Do you have a build log ?

Cheers,

Yikes that price £94 frightening I NEED cheap steppers

someone, somewhere in the UK....

No Build log yet, will do before too long

oh I don't suppose this is very 'attractive really... but I wonder if anyone has built a 'Slanting bed' Gantry to reduce the 'floor size', slanting like a sheet saw type of idea?

[chuckknigh]

I'm terrible at metric to US conversions. How big is 2200nm, in oz-in?

Nevermind, I found a useful site. http://www.onlineconversion.com
According to Online Conversion, the equivalent motors in US measurements would be:
2200 millinewton meter = 311.546251 ounce inch

Obviously these wouldn't work for you...but perhaps this will be of use to someone else. The extremely common HP LaserJet printers (models I, II and III) are all equipped with 100 oz-in steppers, of extremely high quality. One stepper per printer.

I can pick them up for under US$5 each, any day of the week, and remove the stepper from the printer in only a few minutes. The motors are also commonly available on the surplus market, on this side of the pond.

They work great...if they're big enough for your project. And, the price is definitely right.

-- Chuck Knight

[smarbaga]

are you going to make your frame out of that 8020 aluminum extrusion ( with corner gussets )
that stuff is fairly ridgide and light weight , therefore may be able to be placed on a tilting type of table for easy storage.
ps: let me know if you need your kitchen floor cleaned , i will do it ... NO CHARGE

[MrBean]

In the uk, http://www.arceurotrade.co.uk have some 180Ncm (250 oz-in) for £30 each. Or some 220Ncm (300 oz-in) for £39.50

My steppers are 100 oz-in, and run just fine for wood and Aluminium.

Regards Terry.

[Pat2000]

Thanks Chuck, yes I have a few myself of those little steppers but I certainly need about 300 Oz in me thinks tho I must check, I'm lucky to have a couple of nice drives (parker Digiplan) which I scrounged years ago now (I've got to see this 5 year dream take shape!!).

Thanks Terry for that link, thats much more towards my budget - have you used that supplier - are they OK?

Santini - sorry for nicking your thread.

anyone for tea in Dorset, more than welcome!!

[santiniuk]

Pat, no problem, (Actually my Grandad was born in Dorset... I must get down there sometime....)

Your slanting bed idea is something that I have seen somewhere here on the zone. From what I can remember the only real problem was fixing down the material that was being cut. Anything that was 'cutout' would fall down.. if that makes sense

Smarbaga, I do intend to use some form of aluminium extrusion (I think!) but I'm still at that stage where I have a zillion ideas and nothing concrete. I used 80/20 on CNC MKI and it was great to work with. Ideal for the garage too as it has not rusted. I did detect some on my linear slides this week so quicky oiled them to get over the winter months.

The site Mr Bean posted has some real good prices. Well worth a look at.

Well enough rambling time to get some CAD done and get some design ideas out for comment.

Cheers

Shaun

[MrBean]

Thanks Terry for that link, thats much more towards my budget - have you used that supplier - are they OK?

Yes I have used them, although I've not bought any of their steppers, but I'm considering buying some for a project I've been mulling over.

Their service was excellent. No probs.

I got my steppers from www.distel.co.uk (surplus electronics), but I would have got stronger steppers for less money, had I known about Arceurotrade sooner. Oh well.

We should give santiniuk his thread back now...

C'mon.... Where's those CAD ideas?

Terry.

[Pat2000]

...
Your slanting bed idea is something that I have seen somewhere here on the zone. From what I can remember the only real problem was fixing down the material that was being cut. Anything that was 'cutout' would fall down.. if that makes sense

Shaun

Yes, LOL, ok I suppose if it was swarf only, but yes cut- out components and I'll probably play with 'dispensing' paint or glue - LOL out of the question.

the slideways need to be 'loaded' evenly IMHO also, I think it's Mike who's making a wall hanging one at his school (I should address this on his thread LOL). a lot to be said for flat and even loading as far as I can see!

what the prob in your garage mind me asking - space I guess - you keep a car in there? cos you don't really want to move the router too much cos of distorting alignments? unless base is ridgid enough - heavy :frown: (don't say it's the wifes junk - thats not an observation thats permissable :nono:

I have a bit of a damp garage, tho it's largely my fault - it's concrete sectional - tho old mind, I must remove the old steel lifting door - bad news for damp and cold, it's also a bad/old lifting design, I'll probably use wood paneling and fit smaller wooden door.

pardon me harping on - but I think this is important for us guys in the 'british weather'

one thing I'll use is nice 38mm dia 316 stainless bar (scrap-yard find) for the fixed part of my slides (hence the Delrin bearings) so thats not going to rust. ally will be used quite a bit also. I'll have to oil my Trapizodial (Acme) steel rod to try and keep that rust free.

my electronics/pc really should be in a cabinet (obviously in enclosures also) if I keep the PC in the garage (I 'kind-of' have 2) then maybe I'll have a very simple heater idea at the bottom of the cabinet - which I'll leave on - frost protector type of thing - but must also keep out the damp.

[Mike F]

Shaun & Pat,

There should be no problems using linear rails in alternative designs provided the right type of rail is chosen. Some rails are designed to take equal loadings in all directions and these are the ones that should be used. I have just looked up your SSR rails in my THK manual and it gives the following information:

Radial loading for any rail is determined as C (this is the 'Normal' loading perpendicular to the face of the block)
Reverse radial loading is given as 0.62C Dynamic and 0.5C static (pulling the block away from the rail)
Lateral loading is 0.56C dynamic and 0.43C static (pulling the block sideways)

For your SSR20 rails, C is given as 19.6kN static and 23.4kN dynamic. There are approximately 10Newtons to the kilo which results in each block capable of supporting approximately 2 metric tons radially. You will, of course, be using 4 blocks on two rails which gives a typical rating of about 8 tons static and nearly 10 tons dynamic. Now I don’t know what you are proposing but I would suggest whatever it is, the rails will be well within limits

It is interesting to note that when I was researching my design, the THK rep said that customers always over engineer their designs and that you can easily get away with much smaller guides.

Hope this helps,

Mike