New CNC Mill on the horizon

Had a reply from Chai, says it should be 9-10 days from now as something to do with fed ex and HK I did not quite understand but nice to know they are on their way.

So I have been thinking about siting this machine on a concrete slab poured on top of my garage floor which currently is not particularly level. Has anyone done this before? if so what sort of thickness do you think I would need? I was thinking I could lay down about 1" and then screed the top with a self level compound?

Then once I have built the frame bolt that down to the pad (hopefully eliminating too much twist) and then do some of this wizardry with self leveling epoxy?

Does this sound overkill or feasible? I am going to this much effort on the machine I would hate for a wonky floor to put pay to the accuracy.

If your planning to leave in same place all time then I'd just bolt it down something like level then epoxy level.

If your planning to build off the pad then yes it's worth taking time to get flat and level. THE most important bit is building off a flat surface that's not in twist.

Have thought about epoxy levelling the floor.? When I worked for Honda we had epoxy levelled pads for accurately setting Suspension.

Its going to be in the same place for the foreseeable - (until the other half decides she wants half the garage for something)

I was thinking of using the pad to build the frame sections on to make sure they were flat and true (more so than garage floor!)

Then assemble to whole thing on the pad and bolt it down.

How thick would the epoxy need to be? I am just reverting to cost here probably be able to deal with a slab as I can get all that on trade no sure I can the epoxy! heres hoping though :)

Whilst i am here....

.... I have been thinking about how to tackle the bed design. Initially it was going to be steel frame with an ally plate then strips to make up t slots however I am now thinking why not use the steel frame (60mm depth from the box section) as th catch tank for the coolant?

So box section steel frame which is the moveable bed. 20mm thick aluminium strips running 90 degrees to the box section cross members. either an aluminium angle edge maybe something like 4"x1" to prevent some of the splash getting everywhere or just some 3mm steel flat bar on its side welded round the edge. Then on the bottom of the steel box section a sheet of something like acrylic or polycarbonate which is sealed against the bottom of the frame (rubber gasket and a silly amount of bolts) obviously I would need to create some sort of fall so the coolant went back down towards a collection spout.

Would this work? or is there a better way of doing it? Apologies for all the questions today had a boring job to do which required very little brain power!

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Originally Posted by fvfdrums

Would this work? or is there a better way of doing it? Apologies for all the questions today had a boring job to do which required very little brain power!

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My bed is done this way and yes it works fine. I looked at many choices before going this route but all other options where far more expensive.
One large piece of plate with a matrix of holes was the preferred choice but far to expensive and also came with little scope for cock-up's. With the strip system then I can just replace any strips that get damaged.

Many ways and lots are equal or better but IME any that are better will be quite a bit more expensive.

Still no sign of the ballscrews, been tracking the fedex shipment but Chai says fedex had a warehouse explosion or something and now everything has had to be reordered in terms of when its shipped so I guess I am in the hands of the Logistical Gods!

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Originally Posted by fvfdrums

Still no sign of the ballscrews, been tracking the fedex shipment but Chai says fedex had a warehouse explosion or something and now everything has had to be reordered in terms of when its shipped so I guess I am in the hands of the Logistical Gods!

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Yes I'm waiting for stuff has well and it's been stuck in Hong kong for 11 days and just checked it's now in France so hopefully may see it UK next week if the Frogs aren't on strike again, then well hopefully see it in months time after the Lazy arse UK customs decide to process it.!!

Yeah mines just made it to Stanstead, it spent all yesterday in France so looks like things are moving a bit.

So fedex finally arrived this morning with a parcel from Chai,

Packaging was a bit limited compared with the other parts I have recieved from China. Upon inspection it looks like at least two of the longer ballscrews have quite a bit of a bend to them. I dont have a dti to hand but turning them I can see it by eye.

Is this a common thing? and how does one go about straightening them ?

I knew it was all going too well :)

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Originally Posted by fvfdrums

Is this a common thing? and how does one go about straightening them ?

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I've got round it in the past by ordering ballscrews and rails at the same time, since the rails add sufficient strength to the package, but if you're getting the rails elsewhere that's not much use.

How long are the bent ballscrews? You can try clamping it between V-blocks, and pushing down in the middle to bend it back... but it's not going to be easy.

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Originally Posted by Jonathan

I've got round it in the past by ordering ballscrews and rails at the same time, since the rails add sufficient strength to the package, but if you're getting the rails elsewhere that's not much use.

How long are the bent ballscrews? You can try clamping it between V-blocks, and pushing down in the middle to bend it back... but it's not going to be easy.

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Rails already in my possession but ill keep that in mind for the future!

I am going to put it in my lathe later and try and measure how far out it is. But any ideas greatly appreciated

My stuff arrived today has well, wonder if they came on same shipment.? Don't know if dare say this but my stuff is ok but I did have other stuff which supported the screws plus they where only 1300mm long.

Depending how bent then like Jon says V bollock and plenty of force, I've straightened screws before but it's slow process and easy to over do and bend more.
If not too bad then I'd fit on machine and see how they perform, sometimes they can be ok when running and not affect machine too much.?? . . .they can also shake the bastard to bits but worth a try.!!

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Originally Posted by JAZZCNC

My stuff arrived today has well, wonder if they came on same shipment.? Don't know if dare say this but my stuff is ok but I did have other stuff which supported the screws plus they where only 1300mm long.

Depending how bent then like Jon says V bollock and plenty of force, I've straightened screws before but it's slow process and easy to over do and bend more.
If not too bad then I'd fit on machine and see how they perform, sometimes they can be ok when running and not affect machine too much.?? . . .they can also shake the bastard to bits but worth a try.!!

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Mine are only 1050mm long but it was just the 4 ball screws bk12 holders and the ball screw holders in the one package covered in yellow tape and a sprinkling of bubblewrap. Oh well hopefully they are not as bad as they feel but I have a horrible feeling :|

My ball screws from Chai were wrapped in plastic, encased in foam and wrapped in a cardboard square tube/box which was liberally wrapped in yellow tape. Not checked mine yet to see if they're straight....might be doing that sooner rather than later now!!

So......

A fair bit of work this weekend and the basic frame of the gantry is done. Lots of measuring 4 times and drilling once but its all worked out really well everything is nice and square and meets up well could not be more pleased.

I have to say a big thank you to Jonathan for organising for the gantry sides to be cut so quickly, collected this morning and on the gantry by this eve.

Now its started I dont think I will be out of the workshop for a while, good job the missus has gone to South Africa for two weeks!

:)

Another weekend of work and the gantry is really coming together now.

Got the y axis ball screw fitted, motor mount machined and fitted inside the gantry, x axis bearing plates milled and drilled and test fit on the rails on some trestles.

Looks like I need to get some more material together for the z axis!

btw, the x rails are screwed onto the trestles I was a bit concerned one side might just fall off!

Did you really need to over build the base frame that much and how do you plan to attach the ballscrews and motors to the trestles.?. . . . Lol

Looking Good Francis sorry I was too busy to help with machining but looks like it's coming along nicely, keep up the good work. .:encouragement:

probably not but I can always have the parts out and pocket sections of the parts which dont need quite as much strength in the future.

Thanks for all the init and I know your busy so its not a problem :) hopefully it keeps going as smoothly.

That is one meaty and sturdy gantry and quite a good design.

i cannot take credit for the design - well other than my version of...... it was a design jazz put up ages ago that I took the cues from

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Originally Posted by fvfdrums

probably not but I can always have the parts out and pocket sections of the parts which dont need quite as much strength in the future.

Thanks for all the init and I know your busy so its not a problem :) hopefully it keeps going as smoothly.

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!!!!. . .You did realise I was taking the Piss with the comment about over building the Base Frame(trestles). . . !!!!

Don't be surprised if the build and progress slows down they always do at some point and the things seem to fly along then just crawl for no apparent reason.? . . . .Just keep pluging away and it will happen.

Sorry! read it wrong thought you meant the base of the gantry!!!

Yeah the trestles are the way forward in cmc frame work torsionally perfectly no movement and you can fold it away after use :)

Well just ordered the materials for the z axis so thats next, i think there will be a lull before we get the steel framework done and then it will be all the fiddly bits that take the time!

More materials arrived so looks like it won't be too long until the y and z are done!

Plus turned up a few stainless parts for various bits around the machine :)

Are you still going to mount the Z axis motor on 4 posts like in an earlier drawing ? I think it's a better idea to mount it on a piece of box section so that the pulley and belt are inside the box, motor mounted on top.

Eddy,

Yes its still going to be mounted on the 4 posts, the tensioning system is not pictured in the original drawing but is part of the posts. Once the machine is fully constructed I will be buiding some thin sheet covers for all exposed areas and have won some good machine bellows for the linear rails.

Long day in the shop today, but very successful thankfully.

Started out making up a block to machine the front plates on, my combination mill and lathe has one real flaw and that is the spindle working ant any major extension and it becomes very inaccurate so I needed to find a way of building the bed up. So I bolted together a bunch of 20mm aluminium plates and surfaced the whole thing and it worked perfectly, somewhere I could clamp the pieces down safely and solid in order to machine the surfaces near the top of the mill.

I machined up the top and bottom bearing plates first and faced the edge that was going to meet the y axis front plate (as the standard plate saw sits from the supplier seem to have a draft angle of about 1 degree) and then it was onto the main plate which I stepped to fit the top and bottom plate by 5mm.

A few holes and it was all together very nicely, its quite nice making the plates to "fit" the machine thats in front of you rather than having it all made up in kit form I can now see the benefits.

So all in all a very successful day, y axis slides left to right very smoothly with no tight spots whatsoever all dialled in with a DTI.

I have mocked up the z axis so still need to do some machining on the front plate of the Y for the ballscrew and surfacing for the bearings but with this new mill setup this should be a breeze! (won't speak too soon)

It makes a nice job when you have a proper milling machine. I like how you stepped the main plate, it makes a good solid joint, the whole thing looks great.

Originally I was going to have a load of parts cut for me but I as I was not sure my Mill was up to the job, or the long runs needed 400mm plus in some cases however I sort of took the bull by the horns in the end when i couldn't get them all done and bought some good measuring devices which makes all the difference.

Also spending time to get the correct cutters, feed speeds, and DOC are important. Luckily I used to run a large CNC lathe and had a load of high quality end mills left from this which just turn aluminium into lovely little chips so its not so much a problem but like I said the play in the spindle when extended on the mill is not good so trying to get the workpiece as close to the start point of the mill was important. After that is was surprisingly satisfying :)

Looking good, well done. G.

Looking good :thumsup:, getting jealous of everyone's build...especially as you all seem to have lots of nice tools to make it with. (Note to self...must get my DIY spindle mounted in something so I can cut my Ali plate and start making my bits...)

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Originally Posted by njhussey

(Note to self...must get my DIY spindle mounted in something so I can cut my Ali plate and start making my bits...)

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That's a great idea that never crossed my mind, maybe use an cross vice underneath it ?

I was thinking of making a dolly for it out of MDF and using it as a hand router but with lower speed/more torque as got a 104A 24V PSU (2 server PSU's in series) I'm going to use with my 100A ESC and servo tester, for speed control.

Attachment 11742

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Originally Posted by fvfdrums

but like I said the play in the spindle when extended on the mill is not good so trying to get the workpiece as close to the start point of the mill was important. After that is was surprisingly satisfying :)

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Part of your problem with rigidity on the mill will be due to using a drill chuck for milling. Drill chucks are not designed for radial forces, since drills apply a largely axial force. For that reason you shouldn't use a drill chuck for milling as they don't grip very well, in addition to being prone to have higher runout. Get an ER collet chuck and set of collets off eBay and I'm pretty confident you'll see the difference. Just get a suitable size one with the right taper etc...

To add to JB's comments, tapered drill chucks like to come lose and drop out when applying a side cutting force - using something like an end mill in a drill press. So can be dangerous both to you and the part, be safe guys....

.Me

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Originally Posted by Lee Roberts

To add to JB's comments, tapered drill chucks like to come lose and drop out when applying a side cutting force - using something like an end mill in a drill press. So can be dangerous both to you and the part, be safe guys....

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On a milling machine the drill chuck is generally held in with a drawbar, so it shouldn't drop out. However, the drill chuck's poor ability to support the cutter radially would make the cutter prone to dropping...

Jonathan, Thanks for that I will do that and see what its like :) I do always use a drawbar with my mill head as the last thing I want is the chuck dropping out and hitting me let alone the piece of metal I have been working on for hours!

I got on to machining the front side of the y axis plate and it again went very well, managed to get the surface nice and level even though it had to be done in two sections as my mill table is not long enough for one pass.

I then milled the base of the bk mounts and the ball screw holder to get the whole thing to close up a bit more without hogging out more of the aluminium plate than I needed to. I only took a couple of MM off the feet of the bearing mounts but it meant I did not need to cut into the face plate at all.

Ignore the lack of bolts I am waiting on a "top up"

Looking at your picture, you have the Z ballscrews bearings bolted to the fixed Z plate, and it looks as if the ballscrew nut will bolt to the moving Z plate. How are you going to adjust the nut or bearing position, or the guide rails, so that everything is nicely aligned? I've been looking at these details on my own design for a while and am looking for inspiration! I have some ideas, but always keen to re-use other people's work...

Sounds a bit similar to the machine I could do with building...I'll be keeping an eye on your build.
If you're buying on fleabay, just a tip... Don't buy anything online after a visit to the "Trip" (To Jerusalem) :cupcake:
Good luck.

Done plenty of buying after going to the Trip! But no CNC parts mind :)

Looks like the build is moving at a pace now, Z axis looking good.