Xairflyer's first MDF CNC router

[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.

[Mr.Chips]

Thanks Xairflyer, for the tip on "Machine Taps".

Would a machine tap also reduce the possibility of tap breakage when tapping alum? I'v broken a few taping alum, seems the chips stick together and jam, even when backing up ever so often.

Hager

[buscht]

Mr. CHips, You might want to use Tap Magic cutting fluid for Aluminum. It will solve your chip sticking and jamming.

[buscht]

xairflyer, When screwing MDF together I think the best fastener is a confirmat screw. Here is a link that shows how one guy uses then in cabinet work.
http://www.norrod.com/shop/screws/
You don't need that fancy drill bit, but you need a clearance hole (8mm) for the the shoulder and a pilot hole (5mm) for the threads.
This eliminates the tiring tappping of MDF and holds fantastic.

[xairflyer]

Yes I have used these before they are common to flat packed furniture you buy at DIY stores.

Tapping should not be tiring if you use a cordless drill !!