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Re: THE NEW MAKO IS HERE!!!

Posted: Fri Jan 18, 2013 6:35 am
by drueth
4dThinker

This is my stop gap to deal with the gantry sag. I also found you can add paper shims in the center between the gantry and the board to correct the sage so you have the same cut depth in the center as the sides

It can make a big differenc if you are cutting a large area with a lot of detail.

Re: THE NEW MAKO IS HERE!!!

Posted: Fri Jan 18, 2013 7:17 am
by 4DThinker
drueth wrote:4dThinker

This is my stop gap to deal with the gantry sag. I also found you can add paper shims in the center between the gantry and the board to correct the sage so you have the same cut depth in the center as the sides

It can make a big difference if you are cutting a large area with a lot of detail.
Looks like a perfect shop solution, Drueth. Well done and thanks. Do you notice any flex at the top of the back plane? Seems as though to twist it would flex as much at the top as it does at the bottom edge. Preventing it at either end may stop it completely though.

Re: THE NEW MAKO IS HERE!!!

Posted: Fri Jan 18, 2013 1:18 pm
by rungemach
Very nice Aztec Calendar carving, it look super.

In looking at the HD gantry design, it uses bearing rods that are supported mid span where the older pro and plus had no supports there at all. It is easier to see the rods flex on the non-HD units as they flex so much. The mid support certainly helps, but only to the extent that the back plate resists bending mid span. So what you are getting is something like a leaf spring, joined together in the center and free to move at the ends, (since the rods can move in and out of the gantry sides a little.)

The easiest way to solve this, as Drueth has done, is to make the back plate stiffer to resist in bending. Since you can't do that easily on the bearing rod side, you have to do it on the back side.

If I had an HD here, I would probably be playing with it to firm it up as I did my pro.
What I would try would be using square aluminum tube, top and bottom. As 4DThinker points out, the top will be moving one way while the bottom the other. This lifts or lowers the router bit height due to weight as it approaches mid spam, and also from y movement cutting force.

I would try and fit the tubes so that they would bolt to the machine using the existing fastening points used to hold the back plate to the gantry sides, and also holding the bearing mid support blocks to the back plate if possible. So the tube would pick up all those attachment points. The bolts would not go all the way through the tube, just through the near side.

That would lock the gantry sides and the center blocks together through the back plate and use the tubes for strength to resist front back push pull.
A 36 inch long piece of 2" x 2" x .125 wall square 6061-t6 tubing is about 18 dollars at "Speedy Metals" and would probably be cheaper than that at your local metal supplier. (Mine is usually about half of that.) So your two supports would be under 40 dollars total for top and bottom. If you take the back plate off, you could use it to transfer the hole locations to the tube quite easily.

This should not be a big issue on the y bearings (under the table) as your table top is reinforcing the bottom, doing what the tubes would do on the gantry (x) axis.

If anyone has an HD nearby Sarasota Florida, I would love to help them do this modification to see how well it would work.

Bob

Re: THE NEW MAKO IS HERE!!!

Posted: Fri Jan 18, 2013 1:26 pm
by tonydude
Great detail in your carving. What size bit did you use to carve it?

Tony

Re: THE NEW MAKO IS HERE!!!

Posted: Fri Jan 18, 2013 6:36 pm
by EdThorne
Hi Drueth,

That calendar is very beautiful. The finish appears to be metalic with some antiquing. What's your process?

Ed

Re: THE NEW MAKO IS HERE!!!

Posted: Fri Jan 18, 2013 6:58 pm
by Wolffie1
I have finished machining the parts for the spindle in aluminium.
I will be getting the plate material for the gantry sides next week but have decided not to replace the backpart.
Instead I an going to machine a .125" plate the full size and bolt it to the existing plastic one.
That should reinforce it really well.
Cheers
Wolffie

Re: THE NEW MAKO IS HERE!!!

Posted: Fri Jan 18, 2013 7:17 pm
by EdThorne
Wolffie, are you making all of the gantry assembly from solid aluminum? I am interested to see how you make out with this project. The original design has an 1/2" plastic backboard where the rods attach. NWA provided some U-shaped extrusions on the top and bottom of this backboard but these are not tied into the sides of the gantry. They may be more effective if they were as this might prevent some twisting?

Maybe the only reasonable solution is to use all metal as you appear to be doing. This is a little expensive but I could do it in stages. Do you have an estimate on the cost?

Regards,
Ed

Re: THE NEW MAKO IS HERE!!!

Posted: Fri Jan 18, 2013 9:22 pm
by Wolffie1
Yes, I agree, making the U-channels a bit short is a mistake,the sides can still flex.
I expect by the time I have done all the parts (yes, I am making every single part in solid aluminium except the backplate) I guess it will come to around $500AU.
I am not including the cost of having the parts plasma cut because they buggered up the job :(
I have a milling machine and have used that one to fix up the bad workmanship but I have ordered an aluminium blade for my bandsaw and will be using that one for the rest of the parts, less waste.
Parts.jpg
I ended up modelling the sides like this
GantryParts.jpg
The screw holes on the HD are vertical instead of sloped so I had to change the design a bit.
Cheers
Wolffie

Re: THE NEW MAKO IS HERE!!!

Posted: Sat Jan 19, 2013 7:59 am
by drueth
EdThorne, Tonydude

The answers to your questions about the Mayan calendar
bit = 0.50 V bit
paint = Rust Oleum Hammered Metal Gold Must allow 24-48 hours to dry befor stain
stain = Ruet Oleum wood stain color = Kona (almost black) In the link it called for a gell stain but I was unable to find any local.
wood = popular 7 slats were glued up to make a 24 x24' board. The grain is fliped up or down after each board is glued together.
cut time = about 5 1/2 hours Set your feed rate to about 50 and the plunge rate to 20

This link is were I found all the infomation and also the .eps file to do the cut. The file "Mayan Calendar.eps" should be about 2/3 the way down on the first page of the link
http://www.vectric.com/forum/viewtopic. ... r&start=15

Good luck and thank you all for the comments.

PS read the part about adding a circle 0.125 larger than the original file to cause the entire output to look like mine LOOK at the tung of the figure in the center of the calender.

Re: THE NEW MAKO IS HERE!!!

Posted: Sat Jan 19, 2013 8:53 am
by EdThorne
Wolffie1 wrote:Yes, I agree, making the U-channels a bit short is a mistake,the sides can still flex.
I expect by the time I have done all the parts (yes, I am making every single part in solid aluminium except the backplate) I guess it will come to around $500AU.
I am not including the cost of having the parts plasma cut because they buggered up the job :(
I have a milling machine and have used that one to fix up the bad workmanship but I have ordered an aluminium blade for my bandsaw and will be using that one for the rest of the parts, less waste.
Parts.jpg
I ended up modelling the sides like this
GantryParts.jpg
The screw holes on the HD are vertical instead of sloped so I had to change the design a bit.
Cheers
Wolffie
Hi Wolffie,

That is wonderful. It would probably cost me at least 4 times that much because I would need to farm it all out. I don't have any tools capable of doing the cutting. Maybe someday I can justify the expense. Meanwhile, I will have to do less expensive improvements and hope for incremental improvements.

I would really enjoy seeing your finished machine. I bet it is going to be beautiful.

Best regards,
Ed