[Letomoto]

Yeah for sure the belts are gonna be covered ! Just not designed yet , waiting to get the pulleys, belts and steppers orders and put them together physically to prepare the holders/covers designs

[wizard]

Aboutthat dead space comment that resulted in confusion.

You mentioned that you used two beams in your gantry design so that you would have room for a leadscrew. What I was trying to say is that such channels are nit always required and may not be desirable. The reason being is that your linear rails and the Bearing cars that ride on them, form a channel between the often good enough for a leadscrew. The specifics of the parts used obviously comes into play but by leveraging this “dead space” you can reduce build complexity.

The other thing here is that mechanical you want to avoid a heavily cantilevered leadscrew nut bracket. The bracket then becomes a lever arm that can flex or put an undesirable toque on the saddle.

By the way I’m not saying that you should never build in such a gap as a combination of factors can make it to be the right solution. Rather what I’m saying is that I would avoid designing in such a feature first and instead try to mount everything on one beam. If your components don’t allow for a single beam solution then a dual beam approach might be the right idea. The complexity I’m talking about here is getting the two beams assembled and in the same plane. It can be done but the lure is extra work involved.



As for the extrusion comment:


A lot of people assume that the T-slotted extrusions are perfectly flat out of the box. They aren’t and like steel beams may require machine shop work to flatten. Generally they aren’t bad for wood working but may not be good enough for machining aluminum. It really comes down to your expectations but generally people need better results in Aluminum than would be acceptable in wood.

So the extrusion comment was more about nit assuming that they are good enough flatness wise the meet your goals whatever they may be. There is a whole discussion about the precision one can achieve in simply mounting linear rails to t-sootted extrusions.

[Letomoto]

You mentioned that you used two beams in your gantry design so that you would have room for a leadscrew. What I was trying to say is that such channels are nit always required and may not be desirable. The reason being is that your linear rails and the Bearing cars that ride on them, form a channel between the often good enough for a leadscrew. The specifics of the parts used obviously comes into play but by leveraging this “dead space” you can reduce build complexity.

The other thing here is that mechanical you want to avoid a heavily cantilevered leadscrew nut bracket. The bracket then becomes a lever arm that can flex or put an undesirable toque on the saddle.

I did changed my Gantry design using a single steel beam instead of two extrusions , i planned on putting the leadscrew inside of it to protect from dust and chips and also make it look more compact/cleaner. Didnt thought about the distance in between the saddle (now understanding what it is) and the leadscrew would create leverage but it could maybe create a backlash when changing direction and torquing the assembly akwardly . So i should mount the screw on the top of the beam and closest to the saddle .

The steel beams will probably need a little mill flattening/shave to receive the linear rails super flat but i now know someone who have a long bed industrial milling . Also seen some people doing a slow setting epoxy leveling with a channel crossover to equalise both sides of the gantry rails but it looked pretty tricky!


Now my particular questioning for now is about the spacings of the linear rails .... i am reading so many different opinions on many different builds and i didnt found anything that is kinda "standardised" best way to mount them to work on aluminum ... Wondering if i use a 6" tall gantry beam i will have correct distance between the linear rails or it would be better (or really needed) using the 8" tall beam ?

This screenshot is the 8" tall single beam , giving 144mm ( about 5.5" ) distance between the rails centers . A 6" tall beam would let 3.5" of space between them , enough?



on the Z-axis assembly i used is using 137mm distance bewtween the rails centers , is it just to have enough room to house the motion screw or it is needed for accuracy/stiffness ?



And yes the gantry sides bearings should be offset from the beam to limit the torsion of the Z-axis weight , i understand and also not losing too much travel distance with the bearings spacing but what would be the minimum spacing? ive seen builds with the bearings just next to eachother and some builds got about a foot in between them . I understand wood is like cutting thru soft butter and wont put load on the carriages so the bearings dont need much spacing but my aluminum goal would need some more spacing to have a stronger geometry ?

From the Z-Axis assembly i used in my drawing i can see the linear bearings are all together on their rail , not any spacing . Probably the Z-Axis needs less spacing because the weight is alot smaller than the whole gantry total weight so probably needs some more spacing or i could just do the same spacing for the other linears ?

And yes on this screenshot we can see the ballscrew bearing bracket is kinda long , could lever



I am starting to feel annoying with my questions , i am not going to university for this but i am finding so many different DIY infos that are getting stirred together in my brains that i am looking for alignment!

[Letomoto]

And i just started to work another version for the 3"x6" gantry beam and side walls . Going from 3x8" to 3x6" i am cutting down the material bills by about 300$ worths it ! . Also smaller spacing in between the rails and linear bearings , keeping gantry offset , moving the carriage ballscrew on the front of the gantry beam. Noted dimensions of the clearance and spacings. Opinions?

[Letomoto]

Build started !!! Everything TIG weld , now gonna find a friend who has a large mill to shave the gantry beam linear rails flat seats and the steppers will arrive in 2-3 weeks. Spindle order is having lots of trouble with the international transfer thru my bank for a Alibaba system is floating somewhere , still in research to find it... Sent january 7th... Not found yet... Grrrr stressing... and China is going on holidays for 2 weeks and will add lots of waiting time for it....


Now i am wondering what type of paint i should use for the whole frame... I was used to do powdercoating but my oven is too small for this frame... I could do the gantry beam tho...
I also prepared sockets to receive legs and will build the lower frame/enclosure seperately.

[routalot]

Looking good and the welding is very neatly done.

[ericks]

I like your work!!

[fretman_2]

Looks great. How are you keeping the framed squared up with the uneven heating of the welding?

[wizard]

You mentioned that the frame is too big for the powder coating capability you have. If you don’t want to engage a professional to paint I would suggest finding a good paint store. Inquire about urathane and epoxy paints they have suitable for machine tool use. You will need proper protective gear and ideally an outdoor location to apply the materials but in the end you get a very durable surface.

You need to follow the application instructions which generally involves mill scale removal and an aggressive primer. You should end up with a very durable finish that will beat anything from a rattle can.

[Letomoto]

Looks great. How are you keeping the framed squared up with the uneven heating of the welding?

i really took the square and measurements maybe 20 times while going around tacking the beams and used big C-Clamps all around to hold the beams flat on their flat sides and hold the position while tacking soft , rechecked everything and then reinforced the tacks everywhere , re-rechecked angles and square diagonal measurements to be sure it didnt warped while putting bigger tacks who would solidify the joints against warping while doing the full welds

it went good :-)

[Letomoto]

hummmm ... i should wait for the whole building part then run it and will probably have to correct things or add add-ons and stuff .. then when it works all good i will probably dont want to disassemble everything to bring the bare frame to blast and paint then reassemble everything .... aaahhh that is gonna be not fun part haha

[Letomoto]

Hello group !

I am very late in the build thread and i worked alot on my project and it is now working pretty better than i thought !!! Comparing it to my benchtop milling i converted the axis to CNC it is completely stunning for myself and all the things i wanted to start making because the benchtop mill had a tiny surface table and maxed out at 3000 rpm so anything was super time consuming to do . Also the axis movements of the mill was only metal sliding on metal with grease and wasnt superb and had backlash to be able to slide along the rails !

Lots of new things i learned thru this build and it is very satisfying to grow up on my knowledge and enlarge my fabricating horizons !!



Now the project needs a few other things to do

- Setup the ATC tool rack and the script coding

- Setup probably a pneumatic cylinder to pull up the 3D printed dust collector shoe when the tool change will happen and when i do not need it . Also receiving in a week the brush hairs/bristles strip to finish the low end of the shoe . I took a CAD of the shoe on GrabCad and modified about half of the design to adapt it to my setup and printed it in Nylon Alloy910.









- Seal all the joints of the table surface aluminum plates and screw holes to limit the coolant mist dripping under the table and level the whole machine a little bit leaning back (like 1deg.) to collect the coolant drips into a drain channel who will bring it back to a reservoir.

- Making security caps and covers for the Y-Axis belts and gears and ventilate the side frame tubes to not overheat the hidden steppers and also put all the horizontal rails fasteners on them .



- Will also face the table surface i built myself using 4" wide strips of 3/8" aluminum and machined a corner of the sides to act like grooves for anchoring the materials . Took forever to mill this with my maxed out 3k rpm benchtop mill and couldnt do more than 30 centimeters long pass because the tiny working surface .... so all the 13-14 strips needed 6 passes on each to move it along its lenght to groove both sides and running at 200mm/min max and it took forever .... the cost of material of the whole surface bed did cost about 1/6th of the price of aluminum extrusion T-slot plates but it took a trillion more efforts in building .... 168 holes and threads on the bottom plate to hold the top strips , 168 holes and countersink to hide the allen screws heads in the strips , also about 60 holes/threads/countersink to hold the bottom plates on the table frame ... hahahaha




- Working right now on pretty harsh chattering and machined a thicker spindle mounting plate on this router . The first mounting plate is only 3/8" thick and was flexing alot . Measured the flexing when working on the tramming adjustment and on the front dial showed me about 0.060" motion going up when pulling on the nose of the spindle . Took a flat screw driver to pry some points of the full assembly of the gantry to isolate weakness (not violently) and it was very flexing easily thru the mounting plate . Will see the results of installing the thicker mounting plate probably today .



Chattering harsher locations marked with the sharpie around the circular motion , this was the second aluminum test . Played with feedrates and RPMs but it didnt really changed the ringing/chattering




After the tramming the horizontal motion gives a pretty flat surface but the Y-Axis movement we can see it wobbles a bit but the X-axis movement toolmarks are pretty more regular. Probably telling the weakness of the mounting plate makes it resonate and wiggles




- And also finish the harness routing , covers , paint , fine tuning and more accessories !!





Little video showing the easily flexing of the 3/8" spindle mounting plate .

https://youtu.be/l0SQCDfqQ8c


Little video about the new mounting plate of the spindle , maybe lower your volume to not rape your ears or wake-up your wife (or husband or kids)

https://youtu.be/YAL_cB0sMCk

Little video of the whole machine moving the gantry

https://youtu.be/XLqRwtHTw1U

Little video about me playing with the manual button on the solenoid pneumatic valve of the ATC system

https://youtu.be/wVzuNBdUCrQ