One years worth of pics and videos of my 43" x 98" MDF machine FIRST BUILD!!!

[Grunblau]

Some of my work can be found here:

http://www.designdemocracy08.com/node/173
http://www.designdemocracy08.com/node/174

Incidentally, this competition was the catalyst for me building my own CNC. I realized that the true meaning of 'Democracy' is that you build it yourself.

(...supreme power is vested in the people and exercised by them directly...)

[eloid]

This is the basic diagram...

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X
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with eye bolts at the fixed ends to allow for tensioning.

It a bit hard to see where the aircraft cable goes from one pully to the other
side can you edit the picture to show different coloured cables to clearly differentiate the direction of tension on the pullys.....


I think i got the idea....

[alien_X]

Really nice build and CAD work!

You must be exceptionally skilled at Rhino - and at using a bandsaw!

[BackyardWorkshop]

I'm doing the same cable idea (nearly identical configuration too) and I've got some pictures up as well if you want a different "look" at the same idea

http://www.backyard-workshop.com/pro...2.html?start=6

[FandZ]

I really like your cat table. I could see myself makeing it. The chair was nice too.

Some of my work can be found here:

http://www.designdemocracy08.com/node/173
http://www.designdemocracy08.com/node/174

Incidentally, this competition was the catalyst for me building my own CNC. I realized that the true meaning of 'Democracy' is that you build it yourself.

(...supreme power is vested in the people and exercised by them directly...)

[Grunblau]

I'm doing the same cable idea (nearly identical configuration too) and I've got some pictures up as well if you want a different "look" at the same idea

http://www.backyard-workshop.com/pro...2.html?start=6

Speaking of similar ideas... on the bottom shelf of my CNC machine sits some brand new high temp firebricks for making my own aluminum foundry... I am really enjoying your website!

[Grunblau]

I really like your cat table. I could see myself makeing it. The chair was nice too.

Thank you,

The foam I was milling was to make a fiberglass mockup of a very similar design. I hope to produce these very soon.

[ddbuster]

In looking at the photos, I am guessing the following:
you have a round brass acme nut inside of a bearing on one end. At the other end of the nut you have the pulley mounted. Based on your acme rod size, the od of the nut is what 1.25", so you have 1.25 ID bearing with set screws attached to the round nut, and you hawged out a 1.25" hole in the pulley. If I am correct in this assumption, how is the whole assembly attached to the carraiage and how is the pulley attached to the nut?

[pminmo]

WOW!!! Absolutely great looking machine build!!!

[Grunblau]

In looking at the photos, I am guessing the following:
you have a round brass acme nut inside of a bearing on one end. At the other end of the nut you have the pulley mounted. Based on your acme rod size, the od of the nut is what 1.25", so you have 1.25 ID bearing with set screws attached to the round nut, and you hawged out a 1.25" hole in the pulley. If I am correct in this assumption, how is the whole assembly attached to the carriage and how is the pulley attached to the nut?

You can see how the assembly works in my cad sheet... I included this information on the plot so I could check everything...

I used the sleeve of the bearing to transfer the motion to the nut.
I 'turned' the 3/8" shoulder of the aluminum pulley to fit inside of the bearing (so 1.25" OD).
Then, I drilled a 3/4" hole through the pulley to allow the 5/8" lead screw to pass through the assembly.
Then, I 5-minute epoxied the modified pulley into the side of the bearing without the set screws.

The brass nut slips into the other side of the bearing and is held in place with the set screws.

The flanged bearing is held into the MDF with a piece of aluminum plate and screws..

I had planned to attach an anti-wear nut to the other side of the aluminum pulley but I found that this was not necessary and would just add drag...

[ddbuster]

Thank you for your prompt reply. I think I get it now, the flange of the bearing (mounted to the "frame") is what is providing the lateral force. The nut is bolted inside the bearing on one end and the flange of the pulley on the other. I understand how the nut stays attached because it is being held in place by the set screws on the bearing, but the only thing holding the pulley inside the other end of the bearing is epoxy on the flange? I am surprised that the rotational forces don't rip it apart. Unless I still don't understand the construction

[mgandy]

Grunblau,

I am starting construction on my new router. This is my first attempt. I am using cross dowels similar to your design. One question. How on earth did you get your holes to line up and make sure the bolts centered the hole for the cross dowel. I have ruined several pieces already and decided to seek help. Did you use a drill press? I'm using a cordless drill and cannot for the life of me get the holes centered and plumb. Any help would be great.

[Grunblau]

Grunblau,

I am starting construction on my new router. This is my first attempt. I am using cross dowels similar to your design. One question. How on earth did you get your holes to line up and make sure the bolts centered the hole for the cross dowel. I have ruined several pieces already and decided to seek help. Did you use a drill press? I'm using a cordless drill and cannot for the life of me get the holes centered and plumb. Any help would be great.

This is what I used... a self centering doweling jig.


I think these are more like $6 at the HB store... this proved to be a such an important tool for me that I would suggest getting a nice $65 one from Rockler.com

Harbor freight one is a little sloppy in the guide pins...
http://www.harborfreight.com/cpi/cta...emnumber=41345

Rockler...
http://www.rockler.com/product.cfm?p...doweling%20jig

that and a good square to draft the line to the edge of the MDF is all you need!

[mgandy]

Thanks, that should help.

[Grunblau]

... the only thing holding the pulley inside the other end of the bearing is epoxy on the flange? I am surprised that the rotational forces don't rip it apart. Unless I still don't understand the construction

It was a tight fit and the epoxy is inside the bearing between the collar and the sleeve of the bearing as well as between sleeve and the flange of the timing pulley about 3/4" of linear surface. I'd be surprised if these two pieces ever come apart. : )

[ddbuster]

OK, Thank you again. I now understand. I just can't get it out of my head that there is no mechanical fastener between the pulley and the bearing, just ---- glue . But hey if it aint broke, dont fix it! Let me add along with everybody else what a fantastic build you did. Your machine is absolutely beautiful! I plan on using your "rotating nut" design on my project. Having a long span on the x-axis myself, I have been concerned about whip. And your design seems to address that very well. Again, thank you very much!

[The J]

Just wondering, since I cannot find where you mentioned it, what size motors did you go with?

[rhinoman]

very very nice. Now my question is how much did all of this cost you? Probebly alot less then if it was made with aluminum.

[Grunblau]

Just wondering, since I cannot find where you mentioned it, what size motors did you go with?

I used 382 oz stepper package from keling.

[Grunblau]

very very nice. Now my question is how much did all of this cost you? Probebly alot less then if it was made with aluminum.

Thank you,

A basic accounting would be...

~$500 Hardware
~$400 Stepper package
~$300 Leadscrews and nuts
~$200 Stuff i forgot
~$100 MDF

~$1500-$2000 i guess. Not too bad when you string it over 8+ months...

I am now building a more mobile 24" x 36" aluminum and MDF Hybrid... hope to have some progress pics soon!