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Birth of a 4-axis CNC machine #1: T-slot comes home

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Blog entry by DS posted 10-25-2012 04:25 PM 2011 reads 3 times favorited 20 comments Add to Favorites Watch
no previous part Part 1 of Birth of a 4-axis CNC machine series Part 2: Putting it together - a start, anyways. »

I’ve been planning a 4-axis machine in my head for more than a decade now.
Every time I go to put it on paper, I get another idea and end up trashing all my notes.

I have a pretty good idea what I want and the materials I can acquire on the cheap will dictate most of what ends up becoming my completed machine.

I want to be able to do 3 axis machining on a small basis, but also a 4th rotary axis for doing and carving on turnings and 3-D objects.

I’ve found a lot of good componants and they’ve come down in price even since last year.
This T-slot is from an old test bench that my Father had gotten and wasn’t using. He gave it to me as a birthday gift. What he really gave me, was the birth of my new machine. I figure I’ve got just enough here to make up the framework of a decent hobby machine.

There’s no real budget sitting around for this project, so I’ll have to acquire peices out of my monthly budget.
This will be a slow going project. If I finish it within the next two years, I’ll be pretty satisfied. For now, this is what I’ve got.

I spent a couple hours last night stripping this down and cleaning it up. It sat outside for some time and a lot of the bolts and nuts were rusted. They’re all now soaking in oil in a #10 can to clean them up.

T-slot is like the grown man’s erector set. This stuff is cool. This 2” X 2” stuff is way more rigid than I thought it would be. I’ve decided to do a double rail framework to make it even more rigid. It should work fairly well I think.

That’s it for now. Stay tuned. Take notes. Thanks for reading along!

-- "Hard work is not defined by the difficulty of the task as much as a person's desire to perform it.", DS251



20 comments so far

View SPalm's profile

SPalm

4826 posts in 2548 days


#1 posted 10-25-2012 04:48 PM

Hey DS, this will be fun.

Building a machine like this is such a mind consumer. I still keep getting the bug to build another, but too much stuff is in the way. I will watch with delight what a craftsman such as yourself will create.

You probably know, but the ebay 8020 store is a great and cheap way to get the missing extrusions for this.
http://stores.ebay.com/8020-Inc-Garage-Sale

Steve

-- -- I'm no rocket surgeon

View DS's profile

DS

2131 posts in 1086 days


#2 posted 10-25-2012 05:05 PM

Thanks Steve!
It’s seeing the machines that folks like yourself have made that has emboldened me to take the plunge.

I have a short list of things to buy as soon as I can scrape up about $600 with no where else to go. I suspect it won’t be the last short list.

-- "Hard work is not defined by the difficulty of the task as much as a person's desire to perform it.", DS251

View oldnovice's profile

oldnovice

3774 posts in 2033 days


#3 posted 10-25-2012 05:37 PM

You can’t go wrong using the Tslot or 80/20 extrusions! They are strong, versitile, and better than any other solution including custom machined parts.
When I was working I built several production tools using Tslot material and the only dissapointment I had was using the linear slides but then my expectations were too high. They did provide a good smooth movement but the lateral play dissapointed me.

Are you going to use linear bearings?
Stepper or servos?
PLC (would be rather novel), Laguna uses that) or PC control?

Have you looked at the Legacy CNC and their 1/2 axis?
Legacy CNC
Kind of a partial solution to another dimension.

Too nosey, too many question!

-- "I never met a board I didn't like!"

View DS's profile

DS

2131 posts in 1086 days


#4 posted 10-25-2012 06:03 PM

I’m looking at using stepper motors. Servers would we terrific, but I am going to try this on the cheap for this machine.

The controller I am looking at can handle four 3.5A stepper motors and I’m going to max that out. It is a nice self-contained unit that can be driven from the on-board keypad and display (Think manual pulse generator), or, it can be fed by a PC via a parallel port interface.

There is a rotary axis with a 3 jaw chuck and a smaller NEMA23 motor that uses pulleys to gear it down. It looks like it will fit the bill nicely for about $200.

The main conflict for me is the spindle. I really, really, really want an ATC spindle. But, the cheapest one I’ve seen is $2500.00 I can get a non-ATC spindle for under $500 so there is a huge difference. I keep trying to think how to make an ATC and adapt it to a non-ATC spindle, but, no joy on that front yet.

For bearings, if I can find some used THK linear bearings that would be awesome. T-slot systems has a ball bearing slider made for thier products, but I have no idea how suitable they would be for the X,Y & Z axis functions.

The tailstock on the 4th axis will use the t-slot nylon bushings with a locking brake to adjust for stock length. I still need to work out a rack and pinion setup for the X axis and am still entertaining other solutions in that regard.

When I’m done, my machine should resemble the Legacy machine quite a bit I suspect.

All good questions. I don’t mind at all.

-- "Hard work is not defined by the difficulty of the task as much as a person's desire to perform it.", DS251

View Joe Lyddon's profile

Joe Lyddon

7752 posts in 2718 days


#5 posted 10-25-2012 06:23 PM

YES!

This will be very interesting to watch…

That’s an expensive bunch of extruded aluminum there… good stuff!

Thank you.

-- Have Fun! Joe Lyddon - Alta Loma, CA USA - Home: http://www.WoodworkStuff.net ... My Small Gallery: http://www.ncwoodworker.net/pp/showgallery.php?ppuser=1389&cat=500"

View SPalm's profile

SPalm

4826 posts in 2548 days


#6 posted 10-25-2012 06:38 PM

Auto Tool Change – huh, it seems like that would not be the “main conflict” yet. You could always add it later. (?) The price difference is amazing.

But hey, I guess that shows that this is not going to be just a throw together machine.

I love it,
Steve

-- -- I'm no rocket surgeon

View DS's profile

DS

2131 posts in 1086 days


#7 posted 10-25-2012 08:38 PM

The conflict, for me, is between wanting the ATC capability and not wanting to spend that much money.
You are right though, I can delay that decision for quite some time.

Who knows? I might fall into some extra dough next year.

In any case, I am designing a space above and behind the rotary chuck for the tool holders. I should be able to fit 5 or 6 of them there.

-- "Hard work is not defined by the difficulty of the task as much as a person's desire to perform it.", DS251

View DS's profile

DS

2131 posts in 1086 days


#8 posted 10-26-2012 04:07 PM

So, last night I went out and started assembling the framework.

I decided to use the corner brackets on the ends of the rails to make the corner joints because I thought they would look cooler that way. The rails have holes for this purpose, but, to my slight dismay, they are not tapped. So I spent about an hour tapping the holes with a makeshift tap before I could put anything together.

By the time I called it a night, I got one end of the unit assembled and I have a good vision of how it will come together. ( I remember kid’s erector sets being easier than this.)

I’m going to take pictures this weekend as I hope to get the rest of it put together.

BTW, my homemade tap was a bolt which I cut across the threads with my dremel tool’s cutting disk. It worked fair enough, though I think my drill has seen better days driving the tap under lots of torque. I did get a blister on the knuckle of my thumb though—soft hands being what they are. (I cut wood with my computer mouse after all.)

-- "Hard work is not defined by the difficulty of the task as much as a person's desire to perform it.", DS251

View oldnovice's profile

oldnovice

3774 posts in 2033 days


#9 posted 10-26-2012 04:24 PM

I take it you are not using the 80/20/Tslot joint connectors! Those connectors are really strong.

-- "I never met a board I didn't like!"

View DS's profile

DS

2131 posts in 1086 days


#10 posted 10-26-2012 04:30 PM

Yes, I am using the connectors where they apply.

The main reason is the asthetic of it all. I didn’t want open ended rails hanging out in the air.
It actually looks pretty good this way and it is also really strong.

Pictures will follow on Monday.

-- "Hard work is not defined by the difficulty of the task as much as a person's desire to perform it.", DS251

View oldnovice's profile

oldnovice

3774 posts in 2033 days


#11 posted 10-26-2012 06:26 PM

Yup, this stuff I’d strong!

There are end cap cover available that just snap into the extrusions. They do not require any hardware.

There are also groove covers available. These are useful for keeping dirt and/or sawdust out of unused section of the extrusions.

When I was contemplating my own build I was considering an enclosed cutting area with sliding Plexiglas doors for access because I had enough snap in sliding door tracks for two 4’ x 8’ tables.

I am sure you can find these on eBay if you can wade through the over 6,200 items just for 80/20 extrusions. I am lucky as the local Tslot distributer and I are on friendly terms and they are less that 8 miles from my house.

Using these extrusions opens a whole new world of possibilities!

-- "I never met a board I didn't like!"

View helluvawreck's profile

helluvawreck

15893 posts in 1532 days


#12 posted 10-26-2012 06:59 PM

I’ve wanted to do this for a long time. My main hobby was electronics about 5 or 6 years ago. Up until about 3 months ago I hadn’t touched it since that time. Unfortunately for my woodworking I haven’t done anything but electronics for about 3 months, so now I’ve gotten the bug again.

Due to an unfortunate set of circumstances at the plant I am now retired at 62 years old. I plan on trying to earn whatever the SS people will allow me to with a combination of my hobby woodworking, buying and selling on Ebay, and some websites that I have in my mind. Web sites are also a hobby of mine. I have too many hobbies actually.

I am seriously thinking of buying a laser engraving machine and a small 2ft by 4 ft commercial CNC router and they’re both Jim Dandies. Surely with these machines I will be able to make some extra money with my woodworking. However, for some crazy reason I still want to build a CNC for myself. I’m hoping also to get a small milling machine and lathe since I no longer have my machine shop at the plant. So, I guess you could say I’m going to have sort of a busy retirement.

I wish you the best of luck on this project and I’ll be checking it out to see how you are coming on it. May you be happy in your work.

helluvawreck aka Charles
http://woodworkingexpo.wordpress.com

-- If a man does not keep pace with his companions, perhaps it is because he hears a different drummer. Let him step to the music which he hears, however measured or far away. Henry David Thoreau

View JL7's profile

JL7

7222 posts in 1631 days


#13 posted 10-26-2012 10:34 PM

Very interesting….I have a little stash of the 80/20…...looking forward to seeing what you come up with…...

-- Jeff - I have not failed. I've just found 10,002 ways that won't work.

View oldnovice's profile

oldnovice

3774 posts in 2033 days


#14 posted 10-26-2012 10:43 PM

I wonder how many LJ have this stuff stashed away?

Maybe we should setup a swap forum!

-- "I never met a board I didn't like!"

View DS's profile

DS

2131 posts in 1086 days


#15 posted 10-26-2012 11:26 PM

Do you mean like this Trade and Swap Forum?

-- "Hard work is not defined by the difficulty of the task as much as a person's desire to perform it.", DS251

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