[Schuimpge]

Hello All,

Finally took the dive, started on my CNC-router.

Just a bit of back-ground, I have zero experience in this. Do have a reasonable amount of common sense and I like to figure things out by myself, before asking people about it. Internet is a great source of information, and from there, I've read quite some things on what to do, what not, etc.

Straight away, I'm making the wrong start of course by not making drawings, plans and build accordingly.
Living in Thailand, ordering parts from overseas quickly add up to huge amounts of money. So I'll try to work with readily available materials, which means I have adjust plans on the fly if I find something that can be used. Luck would have it that I recently had a large batch of aluminium extrusions coming into our factory, so after carefully dismantling and sorting it, I can now start with a reasonable size machine.
Most of the machine will consist of second-hand/recycling parts and materials.

I am trying to build the machine on a very low budget, so not getting into HiWin rails and such yet.
Arduino and cheap controllers at first and trying to get it working first.
Primary use is wood, but if the stiffness of the machine allows, I might try cutting Aluminium in the future.


Basic cutting table has a size of 950mm x 1200mm.
Gantry clearance will be approximately 150mm.
Gantry for now planned 1200mm 80x80mm extrusion, but this can be made larger (vertical) by using 40x40 or 40x80 extrusions.
4x 1200mm SBR16 Linear Rails (fully supported) ordered and on the way. Was a very good deal I think at USD 100 per pair with 2 carriages for each rail.
Plan is to have 2x X-Axis motor, 1x Y, 1x Z.
Testing electronics will be done with NEMA 17's I have already, but for the router, I'm planning NEMA 23 for now unless I get advise to go bigger.


Basic frame has been put together, just to get a feel for the size.

I started with levelling the table on which the router will be build. Managed to get it to within 0.10 Degrees level.
Main Table stands on 6 levelling feet, wheels still attached but they're off the ground.
From there, side of the base frame is 80x40mm extrusions and the crossmember are 40x40mm.
There's 4 cross-members, but likely will add 3 more. Reasoning behind it is that initially, I might skip putting a bed (MDF or Aluminium) in there and use the cross-members to fix work-pieces.
I have the option to also put levelling feet under the router itself. Undecided as off yet.

On top of the base I've put two 80x80mm extrusions that act as a side-wall and will be used to fix the gantry-rails and the motor/motion parts. With rails and plates to fix the gantry to the carriages, I should come to about 160mm to the top of the cross-members, but with a wood or aluminium cutting bed on top of that, 150mm

[Schuimpge]

One of the first questions I have:

Read on MyCNC that linear supported rails should not be mounted on top, but work better if mounted side-ways?
It baffles me a bit and couldn't find any reasoning for it. Anybody could advise me on that?
Aside from easy mounting them it would give me the height I need for the gantry without having to use heavy side-plates to 'lift' the gantry beam to its desired height.

Thanks and regards,
Luc

[louieatienza]

One of the first questions I have:

Read on MyCNC that linear supported rails should not be mounted on top, but work better if mounted side-ways?
It baffles me a bit and couldn't find any reasoning for it. Anybody could advise me on that?
Aside from easy mounting them it would give me the height I need for the gantry without having to use heavy side-plates to 'lift' the gantry beam to its desired height.

Thanks and regards,
Luc

If I remember, the ratings are for 100% load capacity upright, about 70% sideways, and about 30% upside-down. If you look at the static and dynamic load ratings for y our SBR16 blocks you'll see they far exceed the weight of each of your axes - and you'll have four per axis.

A work bed is nice, and sacrificial piece of MDF allows you to cut through leaving nice clean cuts. Also allows you to easily fix work pieces on by simply screwing them down. Some Bondo and work board surfacing makes it like new again.

[Schuimpge]

If I remember, the ratings are for 100% load capacity upright, about 70% sideways, and about 30% upside-down. If you look at the static and dynamic load ratings for y our SBR16 blocks you'll see they far exceed the weight of each of your axes - and you'll have four per axis.

A work bed is nice, and sacrificial piece of MDF allows you to cut through leaving nice clean cuts. Also allows you to easily fix work pieces on by simply screwing them down. Some Bondo and work board surfacing makes it like new again.

Thanks Louie, that helps a lot. It helps that I have a lot of materials to work with, so Aluminium 10mm machined base will go in and then an MDF spoil plate for the time being

Cheers,
Luc

[wizard]

Thanks Louie, that helps a lot. It helps that I have a lot of materials to work with, so Aluminium 10mm machined base will go in and then an MDF spoil plate for the time being

Cheers,
Luc

One thing I suggest highly is to get the manufactures technical manuals for these components. They go into great detail in how to caculate loads taking into consideration mounting arraignment and ect. They are extensive and most companies offer free access to said materials. It is important stuff to become familiar with because proper application goes a very long ways to success. You don't want to assume some of the designs seen on line represent good design, it is possible to get away with less than ideal. On a lightly used machine poor design might never be an issue.


Manufactures put a lot of engineering science into their technical PDFs to make life easy for you. It is something to take advantage of.

[Schuimpge]

Hello Wizard, thanks for the input..appreciate.
The problem I have is that for the aluminium I don't know the manufacturer. So it's really a matter of over-engineering it where-ever possible.
I do know that the machines where the materials came from where built to order for Intel. We received them to dismantle and that's about it.
Hard to tell where the extrusions came from, at least for me as a noob to this.

Some pictures below of the extrusions. wall thickness for the 40x40mm (4-slot) Extrusions is 1.5mm. For the 80x40mm (6-slot) Extrusions its 3mm and for the large 80x80mm (8-slot) it's 4mm.
Because of the "donor machines" having been built originally for Intel, I expect a high-quality material choice, but that's of little value if you use it in a different application of course.
The machines where test-beds for light. They carried an 800x800mm aluminium plate (10mm thickness) on 1 axle with a large servo-motor to turn it around. (those servo's including the controllers will soon be up on eBay by the way).. Big machines at about 1.5 meters wide, 1 meter deep and almost 2 meters high.

For me the only way to be sure is to use as much extrusions as possible and putting for example that Alu slab on top to ensure maximum possible rigidity for the base of the machine.
After that it will be a matter of testing the precision and limits of the machine. A true Trial and Error process if you like.
Given the size and what I hope to do with the machine, I think I will be ok, but far to early to say it for sure.

Also 2 pictures of the fasteners.. Those alone are a real nice piece of work. Spring loaded balls in it so you can easily push them in and move them to position. Once there, they'll stay still and very easy to fasten a bracket or anything.
Got hundreds of them with 3 or 4 different screw sizes.
Screws, of course I got pretty much the same amount.

So given all this, I can build a machine as strong as possible, but like to keep that within reason of course.
If this first build will be good, I'm all for it to start another couple of builds and put them up for sale, as I have plenty of extrusions, aluminium parts and fittings to do just that.

Cheers,
Luc


ok...pictures:

[pippin88]

SBR rails have different load ratings depending on direction of force.

They tolerate greatest force from the top, pushing down, and do poorly when the cars are pulled up. Putting then "back to back" means that one rail is strong while the other is weak, rather than both being strong or weak at the same time.

Linear profile bearings (eg Hiwin, THK) usually have equal load ratings in all directions.

[Schuimpge]

SBR rails have different load ratings depending on direction of force.

They tolerate greatest force from the top, pushing down, and do poorly when the cars are pulled up. Putting then "back to back" means that one rail is strong while the other is weak, rather than both being strong or weak at the same time.

Linear profile bearings (eg Hiwin, THK) usually have equal load ratings in all directions.

Hello Pippin, thanks for the explanation. Do I then understand it right that while side-ways positioning might not be ideal, but assuming that the torque of the router-bit is larger then the downward force of the gantry-weight, it's the best compromise for rails? In other words, you're putting the biggest forces (side way twisting of the gantry on the top of the bearings...?

Thanks and regards,
Luc

[awerby]

The arduino drives are in scale with your NEMA 17 motors, but neither are going to be much use on a machine the size of yours. If you want to make a really small machine to try out the concept, that would be a place to use them. But you're just wasting time making mounts and fitting couplers for those little motors on that big machine; I'd say get some motors sized right for the job and drivers and power supply to match, and do it right the first time.

Leveling feet are a good idea. Skipping the tabletop is not. As well as providing a sacrificial spoilboard, the tabletop adds significant stiffness to the machine. Without it, it will be wobbly, which is the opposite of what you want in a router. You'll need all the rigidity you can get, especially if you hope to cut aluminum.

[Schuimpge]

The arduino drives are in scale with your NEMA 17 motors, but neither are going to be much use on a machine the size of yours. If you want to make a really small machine to try out the concept, that would be a place to use them. But you're just wasting time making mounts and fitting couplers for those little motors on that big machine; I'd say get some motors sized right for the job and drivers and power supply to match, and do it right the first time.

Leveling feet are a good idea. Skipping the tabletop is not. As well as providing a sacrificial spoilboard, the tabletop adds significant stiffness to the machine. Without it, it will be wobbly, which is the opposite of what you want in a router. You'll need all the rigidity you can get, especially if you hope to cut aluminum.

Thanks for the input Awerby.. For trying with NEMA 17...apologize for not being clear enough. I meant that as drybed testing, not connected to the router. Dont forget I'm completely new to this so I'll have to learn every aspect of the machine from start. So rather do lots of 'dry' testing before anything starts moving on the machine itself...Once I've figured all that out, next step will be ordering the motors sized for the job and install on the machine itself.
Like to add that drivers will of course be sized to match the motors.

Good point on the bed. Will likely have one of the Alu-slabs at work to fill that job. 10mm and perfect flat. Spoil board on top to clamp work

[Schuimpge]

turns out we'll have a 3 day holiday next week.. Need to dive into all the parts at work and make sure I have stock at home to help me through the weekend..
Hope to put in some hours on the machine and move it forward...
Luc

[Schuimpge]

Measured the 40x40mm extrusion with a digital calliper... It's exactly 40.03mm on both sides.. From that, I assume that the spray-paint coat they have amounts to 2x 0.015mm and exactly 40mm is their outside measurements.
So guess we're talking about metric sized 4040 for the small extrusions, 4080 for the double ones and 8080 for the large beams.Lucky me.. I'm a metric guy.. don't understand the slightest about inches, feet, quarters and eights..lol

Compare the two pictures below.. my profile (8080) and a detailed cross-section from a web-page...threaded centres are both 40mm
Slot openings are 8mm on all profiles.. so in the attached pictures.. If I understand it correctly, it is an: 8-40-8080 series extrusion..
8 Slot Opening Size (in mm)
40 Series Name
80x80 overall outside dimensions (in mm)

Cheers,
Luc

[alan_3301]

To be exact, the extrusion series you are working with is 40S-LITE or 40S-VERY LITE
standard 40S series has no corner holes, 40S-LITE has slightly rounded corner holes, and VERYLITE has square corner holes.
yours 4080 and 8080 profiles appear to be VERYLITE and your 4040 looks like LITE to me.

Check this page out for pictures, they are not the exact extrusions, but very close. automation for industry: Metric (40 Series) Extrusions & Accessories, Metric Extrusions (40 Series)

[Schuimpge]

Hello Alan,
Thanks for that bit of information.. very useful. Don't like the "very-lite/lite" part, but ok, got to work with what I have.
And know what I have means that I can work on strengthening the frame as much as possible.
Great info..
Cheers,
Luc

[Schuimpge]

Well, update of sorts. Yesterday got the chance to have more parts delivered to my house.
Had to choose in a hurry as my transport showed up way earlier than expected.

The large Aluminium bed is 10mm thick, 800x1040mm size.
Couple of options I had:
1. cut the bed to size 980mm x 800mm and add another piece to fill the bed to 1200mm.
2. put the bed length-wise in and leave a gap at both sides between the bed and the extrusions.
3. move the extrusions inwards to fit snuggly against the bed.

Number 1 was ruled out quickly as I don't want to start cutting such a plate and messing it up.
Number 2 is ok, not ideal, and would not give the maximum achievable strength of the frame.
Number 3 is my favourite, also because it moves the side-beams inwards and flush with the beam below it. Makes for a cleaner and stronger frame.

Below some pictures of Option 2 and 3.


Picture of Option 2. Leaving a gap.


Preferred Option 3. The 2 beams on the outside will be removed and the cross-members (40x40mm) will be shortened so everything is flush around the table.
The front and back with get a 40x80mm extrusion for maximum strength (replacing the current 40x40mm).

Did also collect a few pieces for the Z-axis.
Aluminium blocks.. There's a few more, so 4 of them for the rail-carriages and then attach the rails to the larger plate.


On top of the blocks another plate for the spindle mount.
Space between the blocks will give me ample room for the screw.


Got carried away a bit..lol.. Isn't that a beautiful start for a frame of a small, high-strength mill?
8 of those blocks at home, several more in the factory..

Enough for now.. finish my lunch and start fishing for some more parts I need for the weekend.

Cheers,
Luc

[Schuimpge]

If you look at the pictures, there's that piece of wood in the background.
It's supposed to become a sign-board for house-number and name.

That piece of wood is the reason I started checking on CNC machines...

Cheers,
Luc

[Schuimpge]

If the extrusions come from the same manufacturer as some of the fasteners, then I think DBasix it should be.
http://www.dbasix.com.sg/product_list01.asp?id=605 Looks very much like the 80x80 profile I'm using, except for the star shaped bolt holes.
Fasteners are the same though.

Cheers,
Luc

[Schuimpge]

Got my miter saw and started with dismantling everything again.
Cut the cross members to 840mm and went for total length of 1300mm to match the 80x80 extrusions.
Fitted in 6 feet and after bolting everything up I put the Aluminium bed in which had a perfect fit.
Had to use a rubber hammer to slowly tap it in and the last tap went like: tap...bang..
Just popped in perfectly. Solid table now

Seems I can't upload pictures..will be tomorrow for that then.
Also starting on the end plates for the X-axis tomorrow

Cheers,
Luc

[Schuimpge]

Pictures...


Detail Corner


Right side.. 3 feet and 5 'tabs' to support the 80x80mm beam that will come on top.


Basic frame finished. Instead of 4 cross-members total, now its 2 full width extrusions at the front and back, 4 in-between.
Each cross-member has 3 corner supports at each side, total 6. Front and Back have total of 4 each.
Very strong frame already before the next step.


Legs... Still in full up-position. Will later lower them, just easier like this to work on it.


Added the sides. They've been bolted down to the 5 tabs in the second picture.


And finally the Aluminium slab in. The fit is so tight that I had to slowly 'hammer' it down with a rubber mallet.
The last bump I gave it returned me this real satisfying: Peng...


Close-up of the corner, all perfectly flush and ready for a nice big end-plate with 6 bolts to hold the motors.

Cheers,
Luc

[Schuimpge]

Awerby, after putting 6 bolts in the top-plate to tighten it down.. (3 in the front, 3 in the back) I hope you'll tell me that's stiff as non else I've ever seen?! lol

But in all seriousness: Any comments of experts on the site regarding stiffness?
There's a total of 32 brackets for the 6 cross-members. Then there's the 10 brackets that hold the 80x80 beam on top of it.
Last, there's the aluminium plate that is really push-fit but will still get 3 bolts on front and 3 on the back to lock it down to the cross-members.

It feels rock-solid.

Cheers,
Luc