Help with circles

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Re: Help with circles

Postby sandman92k » Thu Jan 31, 2019 12:50 am

so lets see if i can explain this, in the picture i posted with this comment, you are looking at the z axis assembly on the x axis... I did some checking today... when the z axis assembly is in the center of the x axis you can get the z axis assembly to flex, i got it flex .60 mm. I watched this very carefully and the flex is coming from the x axis you can see it. so then i placed the z axis at the ends of the x axis and at the ends no flex... so i am certain this is one issue.. however my questions is how do i get the flex out of the x axis in the center, in the second pic you can see i have it secured. any suggestions or comments, i hope i explained this correctly.


IMG-1561.JPG


IMG-1562.JPG
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Re: Help with circles

Postby ozymax » Thu Jan 31, 2019 1:59 am

The gantry cross beam looks like it is made up of 2x thinner sections. Are they bolted together along their length?
If not, then I'd try drilling, say 8 to 10 holes in the channel slots and bolting them together.
You may have to counter bore the holes so that the bolt heads and nuts sit beneath the surface.
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Re: Help with circles

Postby sandman92k » Thu Jan 31, 2019 2:45 am

it is two pieces, so i will try that or try to replace with a solid piece
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Re: Help with circles

Postby dwilli9013 » Thu Jan 31, 2019 3:12 pm

sandman92k wrote:it is two pieces, so i will try that or try to replace with a solid piece


A single piece would work ideally and I know that 8020 comes in thinwall and thickwall versions the beefier you can make this the better.
That being said if you can not get hold of a single piece cross member then by all means bolt the 2 together along their length. You could use the t slots on the front and back to bury the heads of socket head cap screws. If you take you time and drill accurately the thru holes you could actually use drop in t-nuts on the back side to tighten everything up. Just this change alone you should see a noticeable improvement over the existing configuration.
Does you t-slot gantry have holes in the end of it? There is another way to stiffen up the x-axis with threaded rod through those holes. This however is a bit more involved and would require some drilling on your gantry up rights.
I see that you have removed your router for the pics you just posted. Certainly would not hurt beefing up you router mount at this point. With the deflection you are seeing in the x axis I am sure the router mount is adding to that.
If you would like to revisit the rod thru the extrusion scenario let me know. Glad to help if I can. :lol: :lol:
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Re: Help with circles

Postby sandman92k » Thu Jan 31, 2019 4:14 pm

the x axis is bolted on the ends, just not a threaded rod through, i am going to screw the two x axis together to stiffen up and beef up the z axis, put back together and check square and try,


Thanks to everyone for all the help...
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Re: Help with circles

Postby martin54 » Thu Jan 31, 2019 10:34 pm

How did you measure 0.6mm ? I would think if you lower the z axis until your collet holder is nearly touching the table then you will get more than 0.6mm :lol: :lol:
What have you built it for? Any specific type of work in mind ? What sort of materials are you looking to cut & is this a business or purely hobby machine?? :lol:
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Re: Help with circles

Postby ger21 » Fri Feb 01, 2019 12:47 am

however my questions is how do i get the flex out of the x axis in the center,


The simple answer is you can't.

What you have is basically a toy.
Plastic wheels running in extrusion slots will flex.
Extrusions themselves will flex.
Tiny belts stretch and flex.

Then, when people try to upgrade them to make them more rigid, the weakest part flexes even more

These machines are designed to be easy to build and be inexpensive.
Learn to work around it's flaws, learn the process, and move on to a better machine.
Gerry - http://www.thecncwoodworker.com
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Re: Help with circles

Postby sandman92k » Sun Feb 03, 2019 12:43 am

IMG-1573.JPG
IMG-1574.JPG
IMG-1576.JPG



Just a quick update, i added a cable chain, i did the dual belt upgrade on the x axis waiting for for rest of parts to do upgrade to the y axis.. and made a belt clip.. thanks everyone for the help will be testing soon
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Re: Help with circles

Postby Xxray » Sun Feb 03, 2019 7:10 pm

Gerry said it the best - While you should certainly strive to make the machine the best it can be, there are always going to be limitations using a home brew hobbyist setup. Alot of torque is generated making cuts and, like water, will always take the path of least resistance. And in your case, there are alot of paths, not sure of the practicality of trying to shore them all up ,,, And if you did successfully do this, the dinky router itself would likely bog down. Don't like the be a Negative Nancy here but you are going to have limitations with this machine no matter what effort you put into countering them.

In addition to what was said about proper feed rates, plunge, conservative cutting depths and RPM's [sweet spot], always using a good sharp bit will minimize your issue.
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