New cnc Lathe build.

[blighty]

2 words: Centroid Acorn! http://www.centroidcnc.com/centroid_diy/acorn_cnc_controller.html Forum: http://centroidcncforum.com/viewforum.php?f=60 True encoder threading, CSS & proven software.

been looking at them, impressive bit of kit. even down loaded the software for a look see. like the screen layout as well as i will be using a touch screen. problem is shipping to the UK as i will get hammered for tax. would double the price.

 

[DICKEYBIRD]

problem is shipping to the UK as i will get hammered for tax. would double the price.

Sounds like you guys need your own reseller over there. IMO it's worth the money difference between the Acorn and other DIY controllers for the software & support alone.:thumbup:

I loved Mach when there were few alternatives but now, not so much.

 

[blighty]

I loved Mach when there were few alternatives but now, not so much.

we need a lot of things over here...... new government would be good for a start.

yep, mach3 has been good, thinking of sticking with 3 or move on to 4 will also change the mill over to 4 at the same time.
other options would be linuxcnc or change over to one of these chines all in one things.

 

[DICKEYBIRD]

other options would be linuxcnc

If you have decent Linux skills, that's the way to go. Great software, relatively inexpensive hardware (including good encoder compatibility) good support...what's not to like! Alas, it's completely out of reach for me due to my lacking of the needed computer skills.

 

[blighty]

If you have decent Linux skills, that's the way to go. Great software, relatively inexpensive hardware (including good encoder compatibility) good support...what's not to like! Alas, it's completely out of reach for me due to my lacking of the needed computer skills.

looked into Linux when i first started this thread mainly for the its encoder capabilities. as you say unless you have the skills. or find a forum where people have done it all ready. then its a long learning curve.

Gave Fusion 360 a hammering over the weekend. decided to go for the "first" classic slantbed design. will post the cad pics when done... although it does look like every other slantbed lathe.

if all goes well, it will have a 15" swing over the bed. 10" over the saddle and length of 17 and a bit inch. 8 tool ATC. 46mm (1.811") through hole and some other stuff:thumbup: would also like to have a tail stock, but haven't figured out how to do that yet.

Spindle? not to sure how to go about this, as in bearings. at the mo i'm thinking of angular roller bearing both ends, pre load nut on the drive end. some say this is bad because of spindle expansion. others go for both roller bearing at the chuck end, then a plane bearing at the other. this allows for the expansion. had a look at my other lathe that has roughly the same size spindle. that has roller bearing at ether ends. would probably be easier machining wise to have the bearings ether end, but if this is going to cause problems later on, best to know now.

 

[xpylonracer]

Blighty, both slower and less power than the rated output.

 

[ninefinger]

I would recommend blatantly copying a spindle design from a lathe that already exists and works well. I have the drawings of my Standard Modern 1340 lathe (13" swing, 5MT & D1-4 camlock) and they use 2 tapered roller bearings together at the chuck end (actually a double row tapered bearing), and a single deep groove bearing at the far end (6009-2RS not shown).
Mike

 

[blighty]

I would recommend blatantly copying a spindle design from a lathe that already exists and works well. I have the drawings of my Standard Modern 1340 lathe (13" swing, 5MT & D1-4 camlock) and they use 2 tapered roller bearings together at the chuck end (actually a double row tapered bearing), and a single deep groove bearing at the far end (6009-2RS not shown).
Mike

think you're right, go with tried a tested:thumbup:.

I will have to change some things around with how i have done the head stock. but should be better that what i had in mind originally.

looked up double row bearings...... my word, there a bit on the expensive side. the O/D of the spindle is 60mm ( 2.362") a double row for that was £547. single row £95. then started looking at the size of the spindle. if i went to 65mm the price goes up. if look at imperial sizes the price goes down. 63.5mm(2.5") start at £14 up to £768. ill just close my eyes and pic one.

would need to change the dim of the shaft from 60mm to 63.5mm good for two reasons. 1, bigger wall thickness. 2, less to machine off.

 

[ninefinger]

I hate to suggest it but you could (almost) buy a complete lathe spindle cartridge from Alibaba for the price of bearings!
https://www.alibaba.com/product-detail/A2-4-belt-driven-lathe-turning_60569883119.html?spm=a2700.7724838.2017115.32.a2e87b03Ng5jZE

It probably is very close after materials for the spindle are purchased and cheaper if you value your time, even after shipping charges.
However - I have no experience buying using Alibaba so do not take this as a recommendation!

Mike

 

[blighty]

I hate to suggest it but you could (almost) buy a complete lathe spindle cartridge from Alibaba for the price of bearings!
https://www.alibaba.com/product-detail/A2-4-belt-driven-lathe-turning_60569883119.html?spm=a2700.7724838.2017115.32.a2e87b03Ng5jZE

It probably is very close after materials for the spindle are purchased and cheaper if you value your time, even after shipping charges.
However - I have no experience buying using Alibaba so do not take this as a recommendation!

Mike

like the idea (here's the but), but the cost of getting that over here would be a lot. I try not to import stuff from the US because of this. nice find tough and thank you for looking :thumbup:

Got some bearings the other day, so I've been in the shed drawing things up. a few things worry me at the mo. the first is the thickness of the light blue bit. it turned out to be 6mm (0.125in ish) I could go another 2 or 3mm bigger buy changing the screws from 8mm to 6mm but use more of them. going to 6mm will give me more room to make that part thicker.

secondly , is the end of the blue bit. this is all the room I have because of the bearing. will this be enough to hold the whole thing together? but how much load will be on that bit? after all its not an 8ton lathe taking half inch cuts in SS at a million miles an hour.

 

[ozzie34231]

You are well into your own design, but just for the future, buying from Alibaba shipping would be from Shanghi, not U.S.

 

[Wizard69]

like the idea (here's the but), but the cost of getting that over here would be a lot. I try not to import stuff from the US because of this. nice find tough and thank you for looking :thumbup:

That would be a low cost spindle from China, you can buy a large variety of US made cartridge spindles but your pocket book might scream at the cost. If you do a Google search for cartridge spindles in the USA or China you will find a very large variety of off the shelf spindles available. There are advantages to cartridge spindles but also disadvantages depending upon what you intend to accomplish.

Got some bearings the other day, so I've been in the shed drawing things up. a few things worry me at the mo. the first is the thickness of the light blue bit. it turned out to be 6mm (0.125in ish) I could go another 2 or 3mm bigger buy changing the screws from 8mm to 6mm but use more of them. going to 6mm will give me more room to make that part thicker.

Generally you can get two types of bearings suitable for spindle use. Those ground with a preload built in and those that are ground such that you can adjust the preload yourself. That design appears to be one that expects to use preloaded bearings but I'm not sure due what appears to be a shoulder splitting to the two bearings.. If it is your intention to use preloaded bearings I'd go with a more robust mounting solution that keeps the set of bearing together. If you separate the two bearings in a preloaded set, your spacers need to be ground to some extremely tight dimensions to keep preload on target.

Personally I'd prefer a bearing that allows for an adjustable preload myself.

secondly , is the end of the blue bit. this is all the room I have because of the bearing. will this be enough to hold the whole thing together? but how much load will be on that bit? after all its not an 8ton lathe taking half inch cuts in SS at a million miles an hour.

It isn't the size of the cuts but the resistance to chatter and the production of a good surface finish that should be your goal. When you go to these large swings you need to have a stiff spindle and that requires a stiff spindle bearing set to support the spindle. There are all sorts of (lets say classes) of machines out there with the same dimensional specs, how well they perform is often a question of how stiffly they are built.

 

[Wizard69]

I would recommend blatantly copying a spindle design from a lathe that already exists and works well. I have the drawings of my Standard Modern 1340 lathe (13" swing, 5MT & D1-4 camlock) and they use 2 tapered roller bearings together at the chuck end (actually a double row tapered bearing), and a single deep groove bearing at the far end (6009-2RS not shown).
Mike

Nice post! This drawing highlights some of the tolerances one needs to achieve to get a good spindle fit up. One thing missing form this print is the lubrication solution which is often forgotten about with DIY spindles.

I might also point out that some lathes, a Hardinge HLV comes to mind, that use two angular contact bearings spread apart on the spindle. Keeping the two spindle bearings together at the front of the spindle seems to be the modern solution. Some designs even supplement the two bearings with a roller bearing to better handle radial thrusts .

In the end there are many solutions but copying a known good solution certainly removes a lot of risk.

 

[blighty]

great post's Wizard.

the bearing would be the type I preload. the drawing of the bearings in the pic are the outside dim's. I didn't go for scale. I'll post a pic of them tonight might make more sense. think your right on the spacer. I made it 6mm just because. will probably change that to shim, just to take up the slack. when preloaded all surfaces should touch. just like the fixed and on a ball screw.

I'll be nipping down steam engine guy (MJ engineering) next week to see what metal he has in. i can then finish the drawing of the lathe.
will probably start with the spindle and housing. also get the card out and start ordering the hardware..... ball screws, nuts, rails etc.

 

[blighty]

had a look a some metal today. found some nice lumps for the ATC, spindle for the ATC and a few bits and bobs all for the ATC. So all of the material for the ATC (how many time can i type ATC)is ok. apart from the tool holder bit. Thats a big bit of metal, but may be changing it as i think it a bit over kill. The ATC on the Boxford is only 8" think the one i did is bigger.

he had a big lump of cast for the main spindle, but its was 5 3/4" i need 6 and a bit :-(
He can get what i need, just send him a list.

I also need a 10" square for the main plate. only thing he had was a bit of gauge plate, but its only 9.5mm thick. I know gauge plate is strong stuff, but i'm not sure if 9.5mm will be strong enough. good thing about it is i'ts ground flat both sides and parallel. Might try that stress calculator in Fusion see what it says.

Now having a problem with the head stock material. would like something about 15mm thick and at least 8" wide. but cant find any one in the UK that stocks it. Anyone know of a place in the UK?

 

[ninefinger]

I really wouldn't use cast iron for the spinny bits like the spindle, I'm assuming you're talking about cast iron. Failure could result in death. Just think about how cast iron can be broken and imagine your spindle breaking right at the main bearing - sending the spindle nose and the chuck flying! You need a good steel for the spindle, the housing can be cast.
Mike

 

[blighty]

I really wouldn't use cast iron for the spinny bits like the spindle, I'm assuming you're talking about cast iron. Failure could result in death. Just think about how cast iron can be broken and imagine your spindle breaking right at the main bearing - sending the spindle nose and the chuck flying! You need a good steel for the spindle, the housing can be cast.
Mike

with you on the cast iron, changed me mind about 5 seconds after I saw it.

He's got lots of metal in stock, but nothing in the range I need for the spindle. so have to order it in. Ive just had a quick look on the net for what spindles are made from. CK45 comes up a lot also HT steel. I'm down there again Sunday. ill have a look through his order book see what I can find.

all that's left to sort out would be the Z and X axis plate. as I said he has a bit of gauge plate that's will be good for the Z plate, but its only 9.5mm thick. I have a chunk of gauge here that's 5"x1"x 18.5" perfect for the X axis. think this will be an over kill and a bit of a waste of some good stuff.

 

[blighty]

just a quick one....

found a place where i can get everything thing i need as to metal stuff. I can get most of the smaller bits from MJ, but it was the bigger bits that was the problem. Plus one place i found wanted £460 +vat for the spindle material. talking of spindle, been looking stuff up about that..... what do you think about using EN24T?

Still doing the design for the lathe, as i find more bits for the lathe i then have to change something then that changes something else.......:wall: one change in the angle. from what i see most slantbed's are 45deg. if i do this the lathe has to be wider to fit all the X travel. The Boxford 240 was more 55 to 60deg. if i do this, it frees up some room and the lathe can be thinner... more compact, but the lathe bit will still be the same.

 

[blighty]

And we're off!

Still not happy with the design of the main part of the lathe, but in the mean time the ATC is all done, so I have start with that.

as tool changers go, it's a bit of a standard one. just had a look around the old net and came up with something that should work.
As for size.... the tool holder (the hexagonal bit on the left, with out the holders, is about 8inch OD)

I load of metal turned up about 6 weeks ago, but I made a change to the size of the pulleys and don't know how big they were going to be.
ordered them a month ago and they turned up today.

Have turned up all the round stuff, apart from the main spindle. needed to wait for the pulleys to work out the main spindle. plus my lathe isn't big/sturdy enough to handle
EN24T, vibrates like you wouldn't believe. My lathe will cut it, but not 4in di and 13 inch between centres...........need a bigger lathe.

 

[blighty]

turning for the bits in the middle. bit of milling for bolt hole etc still needed. pulleys and the piston. found a bigger lathe, so ill turn that up next week ready for the MG12.