My Newest Desktop machine

[microcarve]

Thanks eSilviu!



I'd say I do believe it'll handle aluminum. Easy to replace if it wears faster
than I'm thinking.

There's one great thing about urethane in that it's easily and permanently glued
with CA glues. That means a felt washer can be directly glued onto the ends
as wipers. Or even end caps machined to be glued in place with both lube
and wipers. Tons of things are possible when a material works so well with
super glue.....and it's *permanent*


John

[microcarve]

Mine is a 5/8" screw equivalent to a 2 start screw. The more starts there
are on a screw the more it could be prone to back-driving.....which
can also be a drawback with ball nuts. Need higher holding torque....which
means larger motors.

2 start stays in the lower motor speeds where the best holding torque
is and the range of useful cutting speeds. Say 50-150 IPM.

The difference here is that the frictionless motion of the ball nut is
swapped with intentionally induced friction of the plastic nut. Lower
power and cheaper motors can do the same work as the ball nut, without
possibility of the back-driving problem.

(thinking in terms of 5 turns per inch...)

I *think* I've got that figured about right. Could be wrong, but I do think so.


John

[microcarve]

BTW....

I'd better go right ahead Now and get my "disclaimers" in place...

Nope, I'm not suggesting this will replace...or improve...on any
industrial components, parts, assemblies, etc...

It's simply an experiment to try to make an inexpensive and homemade
backlash free nut of some sort. The profile of the ball *screw* seems to
be a good way to try it that could possibly work very well and be easily
made by anyone.

The screw isn't much more expensive than Acme, so it's worth giving it
a try. And, so far, it seems like it'd work Great.

Time will tell...

John

[Jay C]

Originally Posted by microcarve <---SNIP--> Even then, the friction can be a problem. But this should have some benefits to it that make it...at least...worth taking a look at. Wax the screw well with some Johnson's paste wax...(as a mold release) John

What about using moglice as the first coat then the urathane on top of it for the structure. Just an off the wall suggestion, I have no experience with either material (though I did buy a sample of the urathane based on your experiments )

[microcarve]

I haven't ever used the moglice material so I'm not 100% sure, but
I seem to recall it's a type of epoxy...(?)...
...which could lend itself to working well like you suggest.

Reason being, it's also a thermoset material that can be "roughed-up"
on it's surface level and have a surface for the urethane to stick to.
And...as the urethane is on the outside layer of the nut, it could be
relatively thick...1/4" or so...making it shrink fit to the moglice layer.

Basically, the two types of "plastic" aren't the slick type that's too hard
to reliably glue anything to....so it could work pretty well.

Best I can judge. I'd say it's worth a try. I'd let the moglice cure and roughen
the surface....maybe make some grooves for physically "locking" the two
layers together...so it'd be completely impossible to separate them without
slicing the whole thing in two.


John

[mactec54]

microcarve
It's simply an experiment to try to make an inexpensive and homemade
backlash free nut of some sort. The profile of the ball *screw* seems to
be a good way to try it that could possibly work very well and be easily
made by anyone.


I have made plastic anti-back lash Nuts for ballscrew & spline profiles before, I use a different material, which is better than what is being used by most for anti-back lash nuts, They work very well, & the friction is not bad at all, This can be ajusted by the length of the nut, & how much load is on it,or work it has to do

[microcarve]

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I get asked about bigger machines...A Lot!....

So, I'm thinking I may go ahead and do my 2nd level prototype of
my "Bulldozer MDF machine"....It normally takes about 3 shots at
a design to get it refined "just right" --for me.

1...Prove the idea works in general.
2...Work on design refining
3...Last refinements and appearance

Not always, but if I know ahead of time it's gonna have to be done
a few times to "get-it-right"...the costs are easier to swallow.
And I don't worry about mistakes so much at the beginning....

Like I've mentioned before, this is a really strong and powerful
machine. And especially so for any MDF machine.

It's relatively easy to make and inexpensive for the rigidity and
strength of it.

Mine should cut about 26 x 15 using the rails I have on hand.
Those rails are some I've had around for awhile and they're 30mm
Hiwin's. At that 30mm thickness, Bolted to 1-1/8" thick MDF stair
treads, it's *extremely* strong and rigid. It simply will not bend
under the power of the best router I have...a Bosch 2-1/4 HP
vari-speed.

There's zero slop in the system and if I use the ballscrews with the
ballnuts I've been experimenting with, I think it'll be maybe the
toughest MDF machine I've seen. Fast -and- Strong...
(Very precise and accurate too!)

I've been explaining the machine to a few people who have noticed
it lately, so while I'm doing all the explaining, I got back interested
in getting on with the finishing of my own. Mine's pretty ugly as
it is and it needs some refining....but when I've used it, it's surprised
me at the sheer "toughness" of the thing. The little white things
on the table are adapters for Wolfgang spindles to fit into Dremel
tool holders. They came out perfect....a bunch of them.

So, I made a few models of my Bosch router to see how things fit
all relative to each other and it looks like it's a nice design that *can*
look nice.

Some more details to go, but I'll be glad to finally get the thing
in use. It's fixed bridge with those overkill rails and simplicity of it
would make a machine like this an Ideal thing for guitar bodies and
projects in that size range.


John

[microcarve]

My original looks so bad because I was going to enclose it.
So I wanted a place to bolt the sides on. The bridge bolted directly
to the table works well enough, but it's not "right". It'll be stronger
with the bridge uprights longer as shown in the model and metal
plates like I use to bolt it all together.

I didn't add an enclosure because I really liked being able to access it all
around like it is. It's very easy to modify or keep clean. Long parts can be bolted
to the table that couldn't if it were enclosed.

I never finished it because it'd be too heavy to sell and ship them, but judging
from what the weight and costs of other machines being shipped are, it could
be reasonable enough to someone. It's a *Very Tough* machine design. Very.

It'll need a table and that'll be about 40" x 36"...and whatever height someone
wants. Easy to roll around and out of the way with some HF wheels on a cart.

It's dirt simple, and it's a Great machine.

Aluminum?...sure it will....


John

[microcarve]

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"Enclosed" meaning similar to this one....



John

[TheRobberDotCom]

Wow John! so many posts, so many refinements

[microcarve]

Originally Posted by TheRobberDotCom Wow John! so many posts, so many refinements

I think I can put my hand on maybe 10 different cnc machines on
any given day. I had a guy want to give me a nice one once and
he was stunned that I told him I didn't need another cnc machine.

I did Thank him Very Much, though...

I make some part or assembly every single day. Sometimes piles
of them. I should've just bought one to start with then I'd be more
interested in *using* them than *making* them.

Oh Well, it keeps me busy....


John

[mmcp42]

it's interesting to compare and contrast your use of MDF to build a beast with David Steele's solsylva design that uses wood because it's so much stronger than MDF

is that because of the smaller size of machines he's building, simplicity of design, or just two different opinions

have really enjoyed your various threads btw
amazing stuff