Luke11CNC Build Log ,I'm so naïve

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Originally Posted by Jonathan

I know, but proper double nuts aren't as good as two nuts and springs / belville washers are they.
When I referred to 'double nuts and a spring' earlier I was thinking of doing something like this as it's a simple way of implementing it:

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Ok as my final comment on this.!! . . Yes and no. Yes Belville washers will apply far more preload but at the potential cost of shortend life.! There is such a thing as too much preload.
So then for that very reason NO it doesn't make them better.!! . . . .They will only be better for shortened period of time, obviously how long depends on Belville force, but they will wear sooner with the ultimate result of a wornout knackerd screw.
If good quality screws with high preload doublenuts are used they will give zero backlash with trouble free service for years, if installed correctly and maintained properly.
Yes they come at an high cost but theres a reason for that, precision costs.! . . . . If it was just a simple case of sandwhich a few Belville washers between 2 std nuts without any consiqences or performance costs then thats what they would do dont you think.?

Anyway all of this is Ballcocks for 99.9% of DIY level machines and certainly cheap C7 chinese screws.

James I appologise for filling your thread with unrelated post's so know I will say no more unless related to your specific build, which this originally kind of did.!

Dear Jazz thank you for the y-axis jigs they have arrived they came on Saturday.
I would like to thank you for your time and for rushing a second set out The first set are no where to be seen
I can only now confirm this as Luke has only opened the parcel.

I did email Jonathan saying they had arrived but I was not a 100% sure Sorry for the delay

James & Luke

I've been looking at my gantry all day and some think is not right and after about 3 hours I decided to get my set square out.


and this is what I found

Attachment 4733
The above image shows that the gantry is out of square by 1.5mm
Attachment 4734
the above image shows the joint is fitting nice and tight (this is the left side)
Attachment 4735
the above image shows the gantry is out by .5mm

am I being to picky does it really matter that much that the Gantry is not square

Well I think so

there is no stress to force the gantry out of square as all bolts have been taken out and the rails are not bolted down the only fixings is the three button bolts in the side of the gantry.

Now I have tried to force the gantry square but it is solid and will not move.

I am at a lost and getting frustrated
what is my options Please Please advise what I need to do :question::question:


James

if you take one side off and measure the depth of the machined groove on each edge to see if the groove is machined level to the face. It may be a good idea to machine the edge of the plate the side is clamping too, to make sure the mating faces are square and flat.

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Originally Posted by JAZZCNC

So then for that very reason NO it doesn't make them better.!! . . . .They will only be better for shortened period of time, obviously how long depends on Belville force, but they will wear sooner with the ultimate result of a wornout knackerd screw.

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I think the spring method will be better for longer as wear with the double nut will lead to more backlash, whereas wear with the sprung nuts will not have much effect. It will reduce the preload a bit, but you can adjust it so it guarantees that backlash is eliminated. Which is pretty pointless on a router anyway...but I know which method I'll be using when I convert my lathe/mill.
Either way for hobby machines they are used so little (relative to in industry) than wear on the ballscrews/nuts is negligible. If you've used it for long enough to wear out the ballscrews then you've probably made enough money to replace them.

James: That not being quite square is one reason that I suggested you used triangular plates from the X-bearing mount to gantry side. They will stop the deflection.

I cut the slots in the gantry sides on my router as they wouldn't fit on the mill. The bad had been surfaced recently, so they shouldn't be far off ... if you want me to skim the bearing mount plates to get them square that's not problem. I meant to do it anyway but forgot.
Bear in mind SBR/TBR type bearings will tolerate some rotational misalignment, so will it make a difference when the machine is running? I don't think so, but I'd still add reinforcement triangles to make sure.

James,
I agree with i2i on this one. It might not be the side plates but the cross axis beam. It might not be perfectly square cut or it might be slightly short. If you have bolted up one side and its a bit short it would give this result when fitting up the other side.

Ian

thank you all Jonathan I will bring the gantry sides with me at the weekend :)

Ian and i2i the cross axis beam is not tight and only has two bolts on each side top and bottom

James

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Originally Posted by Jonathan

I think the spring method will be better for longer as wear with the double nut will lead to more backlash, whereas wear with the sprung nuts will not have much effect. It will reduce the preload a bit, but you can adjust it so it guarantees that backlash is eliminated. Which is pretty pointless on a router anyway...but I know which method I'll be using when I convert my lathe/mill.
Either way for hobby machines they are used so little (relative to in industry) than wear on the ballscrews/nuts is negligible. If you've used it for long enough to wear out the ballscrews then you've probably made enough money to replace them.

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Ok jonathan you seem to know something all the top Ballscrew manufacturers in the world don't so get on with it and good luck.!!

James first I would double check the square is accurate.? Those type of wood working squares are not the best for accurecy.! Ideally you want a good engineers square, longer the better.

The gantry is not neccesorally out of square, check the angle between the cross brace and gantry sides.! . . . Are they 90deg.?
Like as been suggested the cross brace could be short or the rebates in the gantry sides could have been cut fractionly deeper than intended creating the same affect.
If the difference is only small then you could easily place a shim/s in the rebate effectively widening the gantry back to original width and/or use them to bring back into square if rebate is uneven depth or wedged shape.?

Because your using round rail you can accomodate this slight angle difference were the bearing plate meets the gantry side. (Easily fixed with with triangle braces like Jonathan suggests)
Thou it's actually not a big problem if the gantry sides are not exactly 90deg to the cross brace because your using round rail. (If was using profiled rails then yes it would be a big deal.)
Yes ideally you would like absolute square and true but So long as the error is not so great that it affects the screws then you'll be ok

Far far more important is the gantry runs square to the X axis.

I say get your self a good accurate square and some shim steel, It's not un-common to have to use shims to bring things into line or back to square so dont consider it a bodge.!
Far better to hold something square with shims than force it square.!!!

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Originally Posted by JAZZCNC

Ok jonathan you seem to know something all the top Ballscrew manufacturers in the world don't so get on with it and good luck.!!

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All the top manufacturers are aimed at industry where the expectancies (life, accuracy etc) are significantly greater. So if we slightly reduce the life by using double nuts or springs with the same preload it's still going to last a very long time. Most DIY builds don't lubricate the ballnut which clearly is reducing the life expectancy similarly to what we're discussing, however they still run for years... I did consider lubricating mine properly, but when you're rotating the nuts it's easier said than done. Even if you could connect the tube for the oil the oil just flys out.
My comments apply to the C7 screws almost all of us buy where the spring helps compensate for the lead error, not your C1 ballscrew!

James: You can check how accurate the square is by placing 4 equal diameter cylinders in it arranged in a square and measure the diagonals (i.e. placing the caliper across the tangents). If they are equal you know it's good. That's fine in theory... the problem is finding 4 accurate cylinders, bigger the better-I don't advise using your router's rails!

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If you've used it for long enough to wear out the ballscrews then you've probably made enough money to replace them.

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thats the way iv been looking at it :naughty:

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Ok jonathan you seem to know something all the top Ballscrew manufacturers in the world don't so get on with it and good luck.!!

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thats a tad aggressive jazz :eek: .... in this sport there is an element of "art" and "on the cheep" im struggling to knock jonathans logic till i know better..... out of interest has anyone managed to wear out a ball nut in our DIY circle ?
and did they make enough to replace them lol

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Originally Posted by blackburn mark

thats a tad aggressive jazz :eek:

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No "Your talking bo@~#cks Jonathan" is Agreesive but I didn't say that did I.:whistling:

Yes I've worn out a ballscrew, it took 3 yrs and yes it payed for it's self meny times.

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Originally Posted by JAZZCNC

Yes I've worn out a ballscrew, it took 3 yrs and yes it payed for it's self many times.

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You wore out the ballscrew, or the nut and what machine? Did you replace one or both out of interest? Tell me more!

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Originally Posted by Jonathan

You wore out the ballscrew, or the nut and what machine? Did you replace one or both out of interest? Tell me more!

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One of the X axis screws on my machine, it was the screw mainly but the nut was well tired. In it's defense I've abused them and the hole machine to the point of torcher.
99% of the time it's cut aluminium and with absolutly no protection for the screws from chips and flying debris. . . Some times running constant for upto 36hrs non stop.
It also didn't help that in the very early days I forgot to tighten one of the pulleys and it came off. The other screw kept going and very badly racked the gantry bending the screw.
I had it straightened but it was never the same.

Got some nice quality 25mm Ground C3 doublenut screws for my new soon to be machine. The old machine will be retired to just cutting wood an plastics.

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Yes I've worn out a ballscrew, it took 3 yrs and yes it payed for it's self meny times.

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splendid :smile: .... i can live with that, i give mine an injection of grease now and again and they are pretty clean most of the time :whistling: if i cant make em pay in three years ill go back to wiping backsides for a living :)

Hello all

Well the day started of well and it was nice to see Jonathan again
I hope you liked your Hand made card and bits.

I have got a lot of bits sorted out to day BUT as always one step forward and five step's back.

My latest problem is this my gantry is 1003mm wide and with a ballscrew of 1000mm in length all look's fine on paper until you add a the belt pulley that is.

I bought the ballscrew with a standard length on the stepper end of 12mm and need 25mm.

disaster disaster two options open to me well three really

Fuck it and sell the lot

buy a new ballscrew with the correct matched machined end or make it fit.

the way I feel at the moment I could just sell the lot or just throw it away

who need this crap anyway


Sorry Just venting because I'm mad at my self and the wife has been on my case

James:thumbdown::cry::cry::cry:

Lengthen the screw is not that hard if you access to lathe. Dose the nut travel the whole length of the screw? I bought a shorter screw to save a few quid and did just that. So don't panic mister mannering.

I got mine all machined to 25mm.

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Originally Posted by 2e0poz

Lengthen the screw is not that hard if you access to lathe.

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That'll be my lathe then.

I've done that before to add a handle to lathe leadscrew - drilled & reamed a hole in the end then machined a bar to fit. Put a straight knurl on the bar to make it grip, loctite and big hammer to 'press fit' it. Start by machining the bar slightly oversize, then after put the ballscrew in lathe, get it on centre and skim the bar the right size so that it is on centre.

Can't the whole screw be moved along and the bearing mount on the non driven end be moved?

Your almost right Jonathan? The screw is very hard and can easily crack (only the centre is soft). If this is added to the floating end then no need to knurl it, just go for a nice tight slide fit and let the loctite do it's job.

Jonathan,
I cant see how the nut will travel the whole length of the screw either. I think your idea of moving the "pulley" end bearing a bit further in towards the floating end and you can machine the plain section down for him to accept the pulley. I dont think lengthening the shaft would be agood idea particularly if you are going to fit a pulley on the lengthened section. Without some kind of support this will start to wear and wobble.

Ian

You wouldn't fit the pulley on the lengthened end? you would put it on the machines end end keep the nut housing to the side closest the belt end. That is how i have my arrangement and it allowed me to add a 90mm extension to the screw.

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Originally Posted by 2e0poz

Your almost right Jonathan? The screw is very hard and can easily crack (only the centre is soft). If this is added to the floating end then no need to knurl it, just go for a nice tight slide fit and let the loctite do it's job.

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The reason I knurled it is because that's what John S does. Well, says he does at least. Could anneal the very end of the screw to stop the risk of cracking, but that's probably taking it too far.

Putting the extension on the 'floating' end sounds good to me as all it's doing is stopping the screw whipping, not transmitting torque. The other end is probably easier though as the tolerances to fit the pulley are not tight as for a bearing. It depends how much we need to add?

Jonathan the problem wih extending the belt end is as you have pointed out to is torque on the jointed section. As WG said that end can always be machined to allow for the pulley. An even easier solution is to just extend out the floating bearing housing with some ali round bar and mount the bearing in the end?

At the end of the day the KISS approach is always best, less to go wrong

I haven't got a clue what your all taking about but I think I've solved the problem.

If I take the retaining nut off and have the pulley machined to slide over the threaded part and have 2mm machined of the pulley shoulder and fit a grub screw plus slide the other bearing right to the end and cut off the excess ballscrew material It will fit

Attachment 4746

what do you think is this a solution or am I making more problems for my self

James

No one with any advice on my solution ??

James

I take it you're going to replace the bearing clamp nut with a thread in the pulley. If so you'll need a more positive location for the pulley, one grub screw just won't be enough. Possibly a pin right through the pulley and shaft when it's clamped up tight.

Well after a lot of soul searching I've decided to take it down to my local engineering shop and have it rematched if it doesn't work I will have to buy a new one but I'm not going to cut corners to make it work now

and if it works they can do the other one (z-axis) as that is the same

James

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Originally Posted by luke11cnc

take it down to my local engineering shop and have it rematched

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Rematched? Wont they charge a lot :(

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Originally Posted by luke11cnc

if it doesn't work I will have to buy a new one but I'm not going to cut corners to make it work now

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I'll buy the old one if it is spare, then you don't loose out. Just need to get ball-nuts for it and that's my milling machine X and Y sorted. I need to do the end machining myself for that anyway.

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Originally Posted by luke11cnc

and if it works they can do the other one (z-axis) as that is the same

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What is the overall length of the Z-axis screw?

Jonathan the length of the z axis is 400mm

and yes if a new y-axis is required then you are welcome to it


James

Just to let you all know the build is back on


Luke is walking now with shoes on so I'm getting him in the garage at the weekend to work on his CNC machine.

we have so much to do and I am hoping to get the machine up and running by the end of November

James and Luke

well we did do some work on the CNC Machine at the week end and have now mounted the gantry support extrusion to rear beam and gantry sides

Attachment 4809

poor poor Luke "Dad how many more time do we have to take it apart just to build it back up again"


Attachment 4808

at the week end we also started the mounting of drivers in the old computer


Attachment 4811

Now I must admit I did most of this and Luke just did the last one and as you can see he finished mounting the transformer

Attachment 4810

In this image Luke is drilling out the y-axis supported rails as they came blank

Attachment 4812

I'm hoping to receive the y-axis supports from Jonathan on Saturday

so we can fit them on Sunday as Mum is out for the day

any way I just thought I would post a quick update

James and Luke:wink::wink:

Ps

it's Luke's bday next month any suggestions for a CNC related present ??

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Originally Posted by luke11cnc

it's Luke's bday next month any suggestions for a CNC related present ??

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How about one of these. ? ? http://www.youtube.com/watch?v=llRbU...eature=related

What date is Lukes B-day.?

cool a bit out of my price bracket

1st December and he is 11

live he lives that long Lol

James

Hello Jonathan

thank you for replying to my email

here is the image I said I would post for you'r reference

Attachment 4815

I would like to recess these bolts into the gantry sides please 10 holes in total

I hope you understand now ??

James and Luke

James:lol::lol:

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Originally Posted by JAZZCNC

How about one of these. ? ? http://www.youtube.com/watch?v=llRbU...eature=related

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I have watched that too many times.

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Originally Posted by luke11cnc

I hope you understand now ??

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I see ... yes can do that, but is is really necessary (might be a bit awkward to set up)?

PS: Don't let Luke do the bolt up too tight on the transformer because that may damage the windings.

No I suppose not but I will have to make the stepper mount bracket to accommodate the bolts

James

found a bday present for him

http://www.maplin.co.uk/robotic-arm-...terface-266257

James

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Originally Posted by luke11cnc

found a bday present for him

http://www.maplin.co.uk/robotic-arm-...terface-266257

James

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Give up your not kidding anyone.!! . . . . WE KNOW IT'S FOR YOU.:dance: . . .Can I have one Dad.:lol:


I have the proper clamp for that transformer if you need it, didn't realise I hadn't sent it.!

yes Jazz you might be right

I was thinking more along the lines of copying it in aluminium but bigger and more lifting weight as it only lifts 100g max

even to the extent of copying the electronics so we have two

do you think this is do able ???

clamp would be good Jazz

James

Well today I've been over to see my very good friend Jonathan

and I lost a lot of money with out placing a bet or dealing a card
only joking mate

It still astounded me how much knowledge you have in your sweet head and put us fossils to shame.

I really wish I had a friend like you Jonathan growing up.

Any way Luke has just about given up on the CNC machine “Dad you will never finish it” I mean to prove him wrong


All the parts fit apart from the bearings on the supported rails But not a problem I will take them down the road and have them re-cut.

What a twat I am I gave you the wrong ballscrew mount but never mind I will have the mounts machined Jonathan

I will post more Photo’s this week and even a video of what to look out for when new members decide to build there own machine

James:rofl::rofl::wink::wink:

well I've been in the garage again today and fitted a little bit more to Luke's CNC and I must admit it is coming together rather well.

Attachment 4852

The above image shows some items made by Jazz.

the M10 T-nuts work really well I could of gone with the M8's you can buy from JKN but I wanted to spread the load area a bit more.

I am also pleased with the supported rail clamps/guides that Jazz also made me shown in the above image they keep it square and true while Luke drills them.

James:tongue::tongue: