[Drools]

Hi John, I have been sourcing THK rails and blocks for a smaller router one that I want to mill/route Aluminum. It has taken me some time but I sourced 18.2" SHS25 for Y-Axis, 24" SSR25 for the X-Axis and 13" SHS15 for the Z-Axis (fixed gantry design). All for under 150.00US.
Originally I thought to use MDF but I have my doubts about securing the rails to the MDF. Since the MDF will deform when I screw down the rails, how do I make sure I get each screw tightened the same? Maybe I could torque them down?
I could secure the THK rails to a piece of CRS first then bolt the CRS to the MDF but I might as well use 80/20 if I go that route.
What are your thoughts?

[microcarve]

Drools,

What I'd do is use the CRS on the backside of the MDF. Assuming you've
found the thick stair tread MDF...(?)...it'll be fine. Even if not, the 25mm
thickness is great because it's too big to "pull into" the MDF on the front/top
surface of the MDF and won't deform it. Use some big washers
on the CRS...which only needs to be maybe 1-1/4" or so wide...(thicker is
better...maybe 1/4")

You can use the 15mm rails to make a temp Z axis that should be good enough
to make a metal one. I did and it worked OK.

The CRS isn't flat enough to use on the front. The rails need an exceptionally flat
surface and the MDF will be flatter.


John

[microcarve]

Use bolts...not screws. Even if you have to grind down the heads a bit.

It should be tightened from the back with washers & nuts.

[Drools]

So you feel the MDF will not deform.
I do not know what they are called but they but they are used in funiture. They have prongs that dig into the wood and are inserted from the bottom. Take a machine thread of your choice... Do you know what they are called and will they work?

[Drools]

T-Nuts

[microcarve]

I have 2 sets of rails I'll sell for $300 a set + shipping from 30429

That's 4 30" long 30mm Hiwin heavy duty rails and 6 trucks/blocks that are
the wide ones with 4 holes that can be bolted from the top. The ones I personally
like myself --as they make adjusting things easier.

Those are lifetime sets that no hobbyist will ever wear out. They'll always be
100% useful for any future upgrading if desired.

I was saving them to make a couple kits of the big-a$$ machine, but the weight
of shipping all the MDF parts will make it very expensive. It's about as simple
of a brute-force machine to figure out and make as is possible.

That's probably $7-800 worth of parts that'll make the X & Y. Someone can pick
up some small thinner ones for a good deal on ebay for a Z.

That'll make a machine that can cut up to about 26 x 15 x whatever z you come
up with.

There's only 2 sets I'll part with so anyone interested write me at...

john at microcarve dot com

I'd really like to see a few of these machines built and showing off some
highly accurate and nice sized stuff made on them...


John

[microcarve]

T-Nuts

Yep, I used those underneath the table on mine. They worked with
1/4-20 machine screws with the holes in the 30mm rails I used, so
it was easy. The table is nice and flat, so I was able to just use
3/4" MDF for the separate table assembly on mine.

I think they come in mm sizes as well, so you may find the correct size
bolts and t-nuts that'll work perfectly with your particular rails.

The Z carries a lot of weight so I handled the bridge differently...

[microcarve]

MDF deforming on it's surface by having these rails bolted to it isn't
any problem at the thickness you have...25mm...?

But...I did buy some long 15mm ones that I was going to make a kit with.
Those are thin enough that they get humps between the bolt holes
when tightened down....then the truck doesn't run right. Those need a
trued metal surface to work well with.

25mm will be fine. The CRS...if you use it as a big, long thick washer on the
backside of the bridge will be **plenty** strong and straight.

The CRS can be hot rolled from any hardware store. It's just basically a washer.

If you have the thick MDF you don't really even need it if you use some thick wide
washers. It can't hurt, but not really necessary with the stair treads. I would
use it with any MDF that's thinner than the thick tread MDF, though.

It can always be added later as well as everything is so easily accessible.

Upgrade--reinforce as needed. If needed.


John

[.xXACEXx.]

i know im getting in on the end of this ballnut thing,i was thinking of something similar to your idea except with a ballscrew or good quality acme screw (and grinding flats to make the rod into a home made tap)

i was thinking that the flat ~15 deg. angle of the acme would be better for wear than the rounded arch of the ballscrew .although the ballscrew would have more surface area per thread?? (just me guessing) i was wondering if there was a way to test this as for wear and for energy efficiency ,maybe some kinda torque wrench to test for energy to move the screw inside the nut. and as for wear maybe running a 10 pound load back and forth like 10,000 times and test for backlash?

this is prolly alot more than you have time to do ,but maybe not for someone else?? (hint,hint)

[microcarve]

i know im getting in on the end of this ballnut thing,i was thinking of something similar to your idea except with a ballscrew or good quality acme screw (and grinding flats to make the rod into a home made tap)

i was thinking that the flat ~15 deg. angle of the acme would be better for wear than the rounded arch of the ballscrew .although the ballscrew would have more surface area per thread?? (just me guessing) i was wondering if there was a way to test this as for wear and for energy efficiency ,maybe some kinda torque wrench to test for energy to move the screw inside the nut. and as for wear maybe running a 10 pound load back and forth like 10,000 times and test for backlash?

this is prolly alot more than you have time to do ,but maybe not for someone else?? (hint,hint)

Best way to test it is to hook it up & use it...

There're a few reasons the ballscrew looks like a good idea to me...

Let's imagine we slice the thing right in two so we can see the
threads. IF...it were Acme, we'd see a lot of little fins that are
fairly close together.

With urethane...heat is the big enemy and may have something to
do with why we haven't seen anyone do this before. The friction
will soften those fins and they'll give way and force through the nut.

(I've had that actually happen with HDPE nuts before.)

Heat changes the properties of many plastics. In *general*...they're
usually OK til about 200 F or so, then they can begin to soften a bit.

Anyone who ever tried melting some plastic to reform it into something
has likely noticed, the thing they made is no longer the nice plastic they
began with, but now brittle and cracks easy. Plastics...and generally
speaking...have a tight temp range to retain their properties. Else
they can fail.

The urethane is a type of plastic that can be cast easily...as opposed
to those that need heat forming. But the trade off in ease of forming
is it's a little more sensitive to heat. Friction from screws traveling
can easily get to the softening point of many plastics.

Urethane's don't melt like regular plastics, they just get rubbery.
So you can see where it'll just push through a nut if there were
long travels that generate lots of friction and the little fins in the
Acme nut won't last long.

Hopefully though, the round threads in the ball nut version can
be a bit less sensitive and harder to soften and displace. And it
lends itself to using the grease packed set screws as there's no
fins in it....again hopefully to cool and lubricate it.

Casting it can be a problem with acme as well as it tends to get
bubbles trapped between some threads. It needs to be poured
slowly to spiral along the threads to make sure they're all filled
and that's simpler with the ballscrew profile.

I do have some nuts made for acme threads and I've used them for
testing machines in the past, but I've never run one to destruction.
I always guessed it may be easy under load, so I never tried.

The ballscrew nut may or may not work well. If it didn't, I'd guess the
main trouble would be the heat from the screw....but the grease
could offset that.

Acme nuts also may or may not be problematic due to the error in
them. Flip the nut backwards and there could be places along travel
that stress some of those fins in the nut. I'm hoping the ballscrew
is much more uniform and that shouldn't be much of a problem....and
it does look good with the one I made.

I don't know if an entire tap could be made from some scrap ballscrew
material, I haven't got that far, but casting is dead simple. The thing can
be made round, square, triangular, any shape. And as long as someone
may need. Easy to add some sort of wiper just glued in place.

And they can be made as needed for little cost.

I hope it works. I'd like to have tested it out before mentioning it, but
I thought as that may be a while, maybe someone might find it interesting
enough to see if it does work.

I think it could.....time will tell....


John

[rapo]

Your cnc machine is great. I want to star a project like your bur I need to know how to control de machine
I use ez-cam to program a fanuc machining center.
What a want to know is how you get the stepper motors to move?
And what cad/cam software you use to program en control the machine.

[microcarve]

Your cnc machine is great. I want to star a project like your bur I need to know how to control de machine
I use ez-cam to program a fanuc machining center.
What a want to know is how you get the stepper motors to move?
And what cad/cam software you use to program en control the machine.

Thanks rapo!



You can buy lots of different kits with the parts already matched
to work together....

Hobbycnc
Probotix
cncrouterparts
kelinginc
xylotex

That's your electronics and motors....

Then you need software to make it go.

I use Mach3 that runs on a computer with a parallel port.
You can use...

EMC2
Turbocnc
CNCPro


You need to have a "G-Code" file to feed to those programs.
That's a simple file with basically little more than coordinates.
Easily created, read or edited with any simple text editor.

There are lots of ways to make gcode files. From free to very
expensive.

I prefer "Easy & Simple" myself...so I use Vectric software. Not free,
but the time saved makes it pay for itself very quickly.

That's cnc software made to be cnc software from the beginning.
No "jumping through hoops" in hopes of successfully making a gcode
file to make a part or project....as it can be with free software.

Very reasonable for what you can do with it. Very well loved software!

vectric.com


John

[microcarve]

Lots of newbies are always attracted to these smaller and cheaper
machines. They can also be sometimes intimidated by the looks
of Mach3.....which I always recommend to them.

I like it because I can do my designs in VCarve pro and send them
instantly to Mach 3 to do a test run or just see how the file looks
in Mach3.

That computer never connects to the internet, and it stays on
basically 24/7 unless a power glitch resets it. All it does is run the
vectric software and Mach3. Very, Very reliable.

But...Mach3 can be scary and complicated looking. There's a way to
customize the way it looks, but that's not easy. It can be done though
with some patience.

When I first began with it, I didn't know for sure what of all that stuff I
actually needed. So I made a very simplified "screen" that had nothing
more than what I needed.

I still use that dirt simple screen today and never have had any reason
to upgrade it.

Here's the sheer ugliness of it here....

Flickr: kz1927's Photostream

It does what I need and that's all....and has for a good many years...

Don't let Mach3 confuse or scare you. You only need a fraction of what
it does for getting work done.



John

[mactec54]

microcarve

The Screen set is great, the color could be a little different,But this is all you need to run a machine, There's to many buttons on the standard Mach screen Gui

You wanted a new idea, there you have it, sell this simple screen set

[fincsher]

microcarve

The Screen set is great, the color could be a little different,But this is all you need to run a machine, There's to many buttons on the standard Mach screen Gui

You wanted a new idea, there you have it, sell this simple screen set

That's pretty interesting.. Do you have any pics? Show 'em up..

[Scott McCray]

John,

The mounting plate sets you show in this post - I imagine these are sized for the 1 1/8" MDF treads? What size all-thread and bolts are they drilled for? I'm still working on my rough draft plans based on your big a$$ machine design - if I ever get them to a point to be worthy of showing, I'll post 'em with your permission (since they are very derivative - a variation on a theme if you will).

Thanks so much for your willingness to share!

[microcarve]

Hi Scott,

Those are for the 3/4" MDF. Made to see how well it'd work, and it's
Amazingly Strong...

Easy to mill the slot with a 3/4" end mill as those are common for anyone
who has a milling machine.

There's what I personally see as a limit to using the 3/4" MDF in length and width
of a frame...for example. Tightening the tension rods will cause the MDF to
bow outwards, but that's a problem easily enough solved with just a few
more "special" parts.

The thicker 1-1/8" tread MDF could highly benefit from the same part made
in their sizes....and that will be super strong and stable as well. Tensioning can
be done using the same 1/4-20 threaded rod, as it's not likely to need to be overly
wide at even 36" or so.

Those parts make construction very easy as there's only a few holes to drill
and those can be done with a hand drill. Alignment and squareness will obviously
will be better the better measured they are, but there's s good bit of room
for error.

Also notice, I make the frame a bit overly deep on my design. I'm accounting for
using a whole tread at the 11" width of it instead of cutting one into two 48"
long x 5.5" sections to save $$$. Cutting corners isn't a good idea IMO because
the frame needs to be excessively strong and rigid. I think the treads were about
$8 each last time I bought them. That's not too bad to use big thick heavy pieces
that won't flex.

So...the aluminum parts. Using the full 11" width of the treads and making those
special parts. Milling an 11" slot may be a PITA, but it can be 8-9" with no problem.
I have to actually make some and see how they feel before I say for sure. They
may even work as well in 2 parts, say 3-4" length.

With the 1-1/8" thick tread material, there's a great chance the aluminum
parts could be skipped and just use the outside part that doesn't need slot
milling. But instead make dado type slots at the tread ends. Only problem is that's
not so easy to get them just right due to the long length and short width. That
may need a good sized table saw and special fences, etc... to make sure the slots
were square. Along with a special blade as it's not going to work well trying to
slot it with any 1/8 blade a little bit at a time.

The slots are important however they get there. Aluminum or dado. The thing will
be so strong tensioned together that an average sized person can stand on it when
it's sit up on end. It'll last indefinitely and have zero flexibility.

I'm all for posting whatever improvements and designs someone may come up with.
There are really an infinite number of simple, to complex improvements, enhancements,
modifications, etc to do with such a simple machine.

It's too heavy to ship as a kit, so there's a lot of sense in someone DIYing it.

I'd planned on using a piece of 4" PVC behind my bridge to hook to the vacuum
hose out the side. That'd make a vacuum chamber that a few fittings could be
made to run a short length of vacuum hose over and down to the router.
That's just one idea.

The high bridge with the removable vise makes cutting big cases easy. The vise actually
works great with the various fixtures that lock in place. It's done some very precise
making of the wolfgang adapters. The bridge could easily be made so it can easily
be lowered or raised as needed....

This is such a simple and easy to make machine that's fully capable of hard
and heavy duty use all day long using those linear rails. It's so easy to make
it using off sized rails that are plentiful. No "exact" dimensions are really necessary,
if someone is mechanically inclined enough to build it by looking at it....as many
of us are...

The MDF will put off some people, but I'll argue that it's in indoor machine. It can
be made on a cart that'll fit through a door...(measure you door if you intend to
do that. Ask me how I know)....to be rolled outside if desired. It can't use
flood coolant anyway, else it'd need to be basically taken apart and thoroughly
dried after each use, or the steel would rust Very quickly.

Using the thick 1-1/8" MDF will make a real "Bulldozer" of a bad-a$$ machine for
a very reasonable amount of $$. The one I have...with a couple simple changes to
the prototype...would route out something like hardwood guitar bodies all
day long.

With these 30" 30mm rails....if someone wanted to ride it while it cuts, I think
it'd handle it fine....

BTW...I still have a set of the rails for sale. 10 piece set of 4 rails and 6 blocks
for the perfect machine for $300.....all brand new Hiwin stuff, never opened.

Long post, but it's really That Good of a machine. Easy as it'll get IMO.
She may not be pretty, but she's a *Hard* worker!


John

[microcarve]

There are still several details in my 3D model that are missing, as far
as the Bulldozer machine is concerned. Some of those should be obvious,
but some won't be.

I'm working on some better detailed models, drawings and explanations
as I get a little time. Soon hopefully. I plan to rebuild mine into the new
version, but I have to make a long drive to pick up some more stair treads
first. Country living has it's pluses, but being far away from supplies isn't one
of them.

Once the frame is constructed right, it should be able to run like this...

http://www.microcarve.com/upsidedown/qs1010.jpg

...else it isn't rigid enough. Need a bigger rope, though...


John

[Mr.Chips]

Hager,

Is yours a ballscrew or a hi-lead acme? I can't tell if the nut is an
anti-backlash plastic one....or is it a metal ballnut?

John

It's a rolled ball screw with a plastic anti-backlash housing with metal balls.

Hager

[TheRobberDotCom]

@John: I know exactly what you mean, but I expect small-town New Zealand is even worse than small-town US Any updates on the bulldozer, or on MDF-excluding kits?