[xairflyer]

After a couple of months looking, reading and learning about home made CNC machines, I started cutting out my 1" MDF machine today.

As I found other guys threads so interesting and useful I thought I would complete a build diary myself, and if a new person gets one piece of information out of it for themselves then it will be worth while.
Decided my first machine would be the learning platform and I will use simple construction and electronics.


My mate brought his Circular saw with a new MDF cutting blade and we cut everything out lovely and square.

The base is 36" wide x 33" deep, it has a fixed gantry with a table size of 24"w x 16"d.
I think I should have about a 20 x 12 cutting area.

I am using 1" dia stainless tube with a ground finish for the rails and bought a load of abec9 bearings on ebay.

I have three steppers, 1A, 1.2A and a 1.35A all unipolar nema 23 size.
Came across extremly cheap driver board from http://www.kitsrus.com/ (although I bought mine from the UK distributor.)
The K179 unipolar driver board kit was only £9.95 works great had my motors on the bench last night buzzing away.
The board has a manual control of speed and direction so is great for setting up without a pc connected.

Going to use a ATX PSU at 12v and some 6R8 resistors.

I do have some nice new in the box vexta 266 127 ozins motors that I bought from a guy, but I intend to keep them for the next one !

Don't have any fancy cad drawn plans of my machine all on bits of paper. I will see if I can post something to let people see the design.

All for now.

[cncadmin]

Can't wait to see how it comes out! Keep us posted.

[balsaman]

Looking forward to seeing it. Good design for a first machine. Moving Table is simple and acurate. Also nice size.

Eric

[xairflyer]

Thanks for the replys.

Not having figured out how to draw with Autocad yet I done this in - Don't laugh ..... MS Word.

I'm one of those guys that does everything in word.

Hav'nt drawn the Z axis, but you will get the idea, actual machine will be rounded in places, but that is more difficult to draw !!

Might use some linear slides for the Z if I can get them at the right money, if not I will just go with the same pipe idea.

Hopeing to have it together (minus pipes) like this tonight.



Only just figured out how to post an image, thought you could just upload it to the forum.
The FAQ don't have much info on how to do this.

[balsaman]

You can upload it. Click "browse" which is left of "attach file", then browse for the picture.

Eric

[xairflyer]

I never saw a browse button, only thing was a IMG button then I typed in the address of the file I uploaded to my web site.

[chuckknigh]

That was the problem...it seems to want a picture from your local hard drive. It actually uploads the image onto the server, and hosts it locally.

-- Chuck Knight

[balsaman]

Look at the bottom under your message (while you are posting a reply). There is "attach file" and "browse".

E-man

[dlenox]

what is the difference in the abec bearings, on Ebay I see
abec-5, abec-7, abec9???

[HomeCNC]

Look at the bottom under your message (while you are posting a reply). There is "attach file" and "browse".

Eric,

This is always the confusing part for a new poster. You will not see the "attach file" if you use the "quick post" at the very bottom of each thread. You must click on the small button at the bottom of the last post's message that says "Post reply" Then you will be taken to a new screen with all the bells and whistles

[xairflyer]

Yeah I see it now Eric don't know how I never seen it before !!

Anyway, been out in the workshop all evening/night (midnight here now).

Got the two end rails and the gantry sides and front screwed onto the base.

Takes a fair bit of time getting it all marked out, and drilled accuratly.
I have a vertical drilling guide for my cordless drill (like a plunge router idea) so I was able to get all the holes nice and streight.

Decided to go with the tapping idea.
As I was going to use 6mm metric bolts I found the best drill size for the mdf was 4.8 (3/16").

As I drilled each hole I dropped a AN3 (3/16") bolt into each hole to keep it square.
I then drilled out the base 6mm and countersunk the holes for the allen head C/S bolts.

I tapped each of the holes, using a machine tap in a slow cordless drill and it worked great. I then ran thin cyno down the holes into the threads.

So this is the stage I am at. Need to turn up some inserts for the ends of the tubes (rails) and make the adjusting blocks.

What is the best material, I was thinking about nylon or similar, don't think even the 1" mdf will stand up to it.

[xairflyer]

Don't know a lot about the bearings but I do know that abec 9's are water proof, 7's are classed as sealed and I would think that the 5's are probably just shielded.

I have both 9's and 7's and the 9's are definatly the better.

[ger21]

The different ratings have nothing to do with seals or shields. And I'm pretty sure that none of the abec 9 bearings (skateboard bearings, anyway) on Ebay arer waterproof. The difference is, the higher the number, the tighter the tolerances are. Generally, if you're gong to use them on some type of tubing ala JK, it won't really matter all that much. But if you can get abec 9 bearings on Ebay for $5 or so, no reason not to get the best if you're paying the same price.

Gerry

[balsaman]

What gerry said about bearings is correct.

Nice job so far AirX. Use Plastic, PVC, or aluminum for the adjuster blocks. MDF is not tough enough. I have heard you can buy a cheap plastic (nylon?) cutting board from wallmart that will work for those and some other plastic parts. About 1/2" thick.

E-man

[xairflyer]

Got my table made up today with the angle down each side and the bearings fitted.

I bolted the angle to the MDF with 6mm Stainless Hex bolts. Four underneath and three on the side.

Surprising the time it takes, just to mark and drill the angles, so as to get the correct distances for the bearings, as they sit on the rail at 90 deg to each other.

You can see in the pic the black engineers marking ink (well a large permant marker !) used to see the lines on the alloy as I marked everything with the height gauge.

The time I have spent on getting everything as accurate as possible I started to think I should have went with the all aluminium version now, but I am determined to build a MDF machine, as simple and cheap as possible.

The alloy machine can come later.

Got my end plates drilled as well for the tubes (rails) and I am picking up some 25mm (1") nylon tommorrow to make the "four jaw chucks" for setting up the rails.

My local steel stockist cut up some 2" x 1" box section to my requirements today, so I can start welding up a frame/table next week to set the machine on.

Fitting the stepper and lining up the drive screw has got me thinking.
What I was going to do was mark a spot as accurately as I can on the drive plate under the table, and then drill a larger than the drive screw (5/16") clearance hole.
Fit my drive nut to the drive screw then bolt this to the plate, does this sound correct ?

What would be the best method of connecting up the 1/4" shaft to the 5/16" drive screw. ?

[xairflyer]

Forgot to add in last post, the bolts I used for the bearings were socket caps (as you can see), 8mm x 40mm but the good thing was they had a plain shank of approx 8mm long which was a perfect surface for the inside of the bearing.

I fitted a thin Stainless Steel washer each side of the bearing then tightened up a S/S Nyloc nut against it. No play or slop at all.

The bolts are a bit long, and I have them fitted with std nuts temporarily at the moment.
I am on the look out for a S/S version of the bolt, about 10mm shorter, but might be harder to get the plain shank.
Good thing about stainless is you can cut it without it rusting !!

[DaSigntist]

Looking Good!

If I might ask.....Why the stainless steel on any part?
Seems like an unnecessary cost.

"Fitting the stepper and lining up the drive screw has got me thinking.
What I was going to do was mark a spot as accurately as I can on the drive plate under the table, and then drill a larger than the drive screw (5/16") clearance hole.
Fit my drive nut to the drive screw then bolt this to the plate, does this sound correct ? "

What I did was mount one side and run the axis down to the other side to match it.

"What would be the best method of connecting up the 1/4" shaft to the 5/16" drive screw. ?"

If you referring to the motor to the drive screw I gut got some reinforced rubber tubing with hose clamps.

[chuckknigh]

On mine, I got some reinforced air tubing, and actually tapped the 1/4"ID tubing with a 5/16" tap.

I screwed it in, and then slipped in the 1/4" shaft -- some worm clamps to hold everything tight, and it worked great.

Or, you can get some of those flexible couplings from McMaster-Carr...they have a standardized mating connector at the center...the two ends can have different sized couplers.

-- Chuck Knight

[xairflyer]

The reason for the stainless is I hate rust, being from an Aviation background it is always a no, no.

The climate in Ireland would be much more damp/moist and even in a workshop untreated steel items don't stay shiney for long.

The other reason is I generally have loads of stainless nuts, bolts washers about as I use them in my buisness all the time.

Not much difference on cost, I can get 100 M6 nyloc nuts for only about €2 more than standard ones.

[xairflyer]

Great idea chucknigh, I will use that. Can't believe the stuff I am tapping these days !

On the tapping front, Yesterday I could'nt find my 6mm machine tap (located later in my pocket !) so I used a standard hand tap as I only had one hole to tap.

Well Massive difference the quality of the tapped thread was nothing like what I got with the machine tap.

The reason I went with a machine tap from the beginning is I know from experience, if you want to tap without having to back off to break "the chip" like normal, then a machine tap is the way to go. The flutes are designed to take the chip/swarf (in the case of steel) out in one piece, so you can go streight in and streight out, perfect for tapping with a cordless drill.

So my advise is, when tapping MDF get yourself a machine tap rather than a hand tap and you will get perfectly tapped holes everytime and easy to using a cordless drill.