Looks like good progress.
As Jazz mentioned you now need to consider trunking and cable runs, at the moment any vertical runs are awkward.
I'd also consider putting the contactor in the high voltage section.
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Looks like good progress.
As Jazz mentioned you now need to consider trunking and cable runs, at the moment any vertical runs are awkward.
I'd also consider putting the contactor in the high voltage section.
Here's a couple of pics of boxes which might help give some ideas, These range from tiny 300x300(red) to 800x600 boxes.
There's no one way which is better than any other so don't stress over it, just be mindful of high and low voltage wire separation along with grounding and you won't have any issues.
Attachment 27564 Attachment 27561 Attachment 27560
Attachment 27562 Attachment 27563
Attachment 27565 Attachment 27566
Thanks, Some useful ideas there Jazz, with everyone staying close to home at the moment, I had some time to get the E-stop working along with fixing DIN rails and mapping out where things will go:)
After attempting to drill the first 16mm hole in the cabinet with a normal bit I realised what step drills are for and did the rest.. great tool.
Attachment 27632
Attachment 27633
Hoping to have linear motion parts finally this week from BST. Physically building again is starting to feel more daunting then the electronics now.!
Thinking about limits and home too -
From what I understand a limit and home can be the same physical switch.
So I'd expect you need a limit on each end of X axis, with one end doubling as a home. Then the same on Y, and Z can have a single switch passed on upper and lower limit, and say upper can be home.
So not sure why people mention 2 X's being used - surely both limits are at the same point as the 2 X axis are parallel?
Edit - Fuse question. The Transformer will be 750VA - 2 x 65V output. I ordered 10A D curve MCB seen on others diagrams, but I'm thinking 750VA/230V is approx 3A so 10A is very high. Or am I missing something (most likely)
Ryan
Ok well regards the X-axis having 2 switches this only applies if you are using twin screws, one side will have a switch that works for limits and home, the other side as a switch just for home. Reason being you home each side independently to square up the gantry. But you only need a limit on one side.Quote:
Originally Posted by CNCRY
Now regards having a switch at each end then there's another way, which IMO is the best way and uses just one switch on each axis.
You place the switch on the moving part ie: Gantry and Y axis which then looks for a target at each end of travel. The Z-axis just uses a fixed switch at the top of travel which looks for the target on the moving part.
This means you have less switches and less wiring to go wrong.This can be done with either proximity or Microswitch type's.
I believe that D curve MCB is sized to cope with the inrush current. A 1KVA transformer will only need approx 4A in steady state on UK mains (varies with min input voltage and efficiency) but the inrush can be something like 100A for a very short amount of time (dimming lights anyone?).Quote:
Originally Posted by CNCRY
Hi Jazz - So as I have twin X screws, if I go for the moving option on gantry I just need the single physical switch on each X (one acts as limit/home the other just home) and I have contacts at each end the switch triggers?Quote:
Originally Posted by JAZZCNC
Then Y needs only one switch using same setup?
Thanks
My linear motion parts are finally here! Happy with the service from Fred at BST - all parts received and in good order. Took a fair few extra weeks but with the worldwide situation at the moment not at all surprising!
Attachment 27672
Looks like most aluminium supplies however are shut so maybe time for more electronics..
So today's question - does anyone know of a coupler for a 10mm end of the ballscrew to a 10mm with 3x16 keyway (on the motor shaft)
I got a load of "oldham" couplers from BST but they are 7mm/10mm bore with no keyway. Stupid question but does the keyway detach?
The problem is the hybrid steppers are not standard 7mm shafts!
Thanks
Ryan
Yep works exactly as you describe.Quote:
Originally Posted by CNCRY
So I was about to mount my 750VA Toroidal transformer to the cabinet back board with the supplied fixing bolt, metal plate and large rubber washers
e.g this kit > https://airlinktransformers.com/imag...photo1_CM5.JPG
Plan was to drill and tap the metal back plate and secure the bolt into it.
Then I read this - https://diy.stackexchange.com/questi...-metal-chassis
From what I understand the bolt itself plus the top mount plate and chassis can form a C shape around the winding and induct a current. People mention fires and things blowing up which I'd like to avoid!
So now I'm thinking to mount to a phenolic (insulating) sheet so the mounting bolt does not touch the cabinet back plate directly. The transformer also has an earth wire.
Any issues with this, or better suggestion people use?
Thanks
What you MUST NOT do is connect anything to the bolt on the top side that is connected back to the chassis as that would then make a shorted turn. The rubber washers are there to protect the transformer for mechanical damage to the winding.Quote:
Originally Posted by CNCRY
The power of the internet! One of the key attributes of toroidal transformers is a very low flux "leakage" which will limit any potential induced current. I understand the argument but would challenge the actual risk - if I had a toroidal going spare I'd set up an experiment (it's interesting, and this is the first that I've heard of it, and the evidence from the internet looks to be more anecdotal than academic). Actually, because of this thread I've ordered a toroidal just for this experiment - I'll report back in a few days. My thoughts are any current is likely to be measurable but insignificant. The risk can be mitigated in any event by isolating (air gap) the top of the bolt from the chassis to avoid the short.
Edit: What Clive said. The more I read the more interesting this experiment might be.
Wow!, just... Wow! I take back everything.
Following the previous post I'd realised I have a bench PSU with a chunky toroidal transformer that I'd previously hacked to pieces. Sounds like a good experimental platform. Ignore all the crap on the bench - I really need to tidy up.
Pic 1: General topology, next-to-nowt resistance (0.1R) from the top of the mounting bolt to the chassis.
Attachment 27703
Pic 2: Open circuit Vacrms reading from the top-bolt to chassis - about half a volt. A lot more than I'd expected and enough to ignore the fancy stuff with a shunt resistor and 'scope, and go straight for the "blow-the-hell-out-of-the-meter" probe...
Attachment 27704
Pic 3: Current short, top bolt through meter and 3 metres of meter leads to ground. Some 3.1A.
Attachment 27705
So, yeah, isolate that top bolt!
I'm going to throw a spanner in the works here and point out that I've built dozens of machines that use the bolt thru chassis method with rubber pads and I've never had any issues with shorts, fires or getting zapped with stray volts/current etc.Quote:
Originally Posted by CNCRY
Like Clives mentions it's a Big No No earthing to the bolt but other than that then you won't have any issues provided the transformer sits on the rubber pads.
So just get on with it and don't worry is what I'm saying. If you want to put a rubber washer on the bolt then why not for what it costs but I wouldn't mess around with Phenolic boards etc.
Thanks for all the replies - I wasn't expecting a full on experiment Doddy :) Good to have some real results though as everything I found was purely theory, no-one tried it until now!
So in summary if the bolt is used along with the chassis to form a "loop/partial loop" around the core then there is some serious potential for amps to flow, but its low risk if the bottom of the bolt only contacts the chassis, as Jazz mentions this is commonly done with no apparent issues.
I happened to have a piece of phenolic offcut so ended up using that on some spacers, plus the bolt itself has a rubber washer between the head and the metal transformer plate. Probably overkill - and I'm sure I'll do something else instead !
PS before I power up.. Red and Yellow (Vsec from each secondary) and Orange/Black (0V) are connected together - is that all correct for parallel?
Attachment 27708
Attachment 27709
Ryan
It was an interesting and eye-opening (for me) quick test - I've learnt from it so all is good for me. Don't blame Jazz re. the mounting method - that's how industry does it - single bolt through the grounded chassis. As Clive says the two rubber sheets are a form of mechanical protection to allow you to positively clamp on the transformer windings without deformation of the windings and compromising the insulation coating on those windings. The sequence is chassis (bottom) -> neoprene washer -> toroidal transformer -> neoprene washer -> steel plate -> nut.
Re. colours - that's a less than useful label on the transformer but I'd interpret it the same as you say - positional reference indicating the phase of the windings. I've had a quick look on Airlink's website and there's no further useful information that I could spot. Your fuse will tell you if it's wrong.
I've missed the earlier conversation on this but guess you're using AC to power the stepper drivers (no sign of provisioning for rectifier and caps) - I'd think carefully at this time of routing the secondaries in a tidy(!) route away from any low-level signalling, to the drivers - I'm sure you're looking to route to the top of the picture of the box.
Ye go on blame me I've got wide shoulders I can take it..:joker:Quote:
Originally Posted by Doddy
Quote:
Originally Posted by Doddy
Here you go you blind bugger.
https://airlinktransformers.com/post...echnical-notes
Admittedly - I just looked at the technical data for the transformers, e.g. https://airlinktransformers.com/prod...ange-cm0750255 ... which you really would think that they'd replicate that most basic of info. Even on the link you provided there's no clear statement as to the phasing of the windings (I've seen better data sheets).
Edit: Actually, I take that back. The link you provide does, in the schematic symbol, give the phase relationship of the tails.
So the transformer lives, and nothing exploded/shorted etc! I did a quick reading across the output and its 70V, which is higher than the 65V its rated at. Is that normal with no load applied? The drivers are up to 70VAC and don't wan't to fry them..
Made some progress over the long weekend - if only I had a CNC machine this would be so much easier:)
Reading some of the new threads I've been re-thinking and slightly concerned that the accuracy I'm building too could result in inaccurate final results.
As this is all "by hand" and printing 1:1 scaling, drill holes are perhaps up to 1mm out, I'm using a digital caliper and angle measuring device during the build, but check as much as possible
There is some slight adjustment by the hole sizing on everything - how much can the software make up for sub mm "corrections"
Maybe overthinking it - but also don't want to end up with something not accurate after all the effort.
As I haven't owned a CNC machine before I don't know what accuracy I'd like, but for example if I could produce something like the Aztec calendar I'd be happy..
Some photos of current build.
Attachment 27802
Attachment 27803
Attachment 27804
Thanks
Re. your 70VAC. The rated 65VAC would be at the rated power of the transformer, and off-load (or lighter loaded) you would expect the terminal voltage to rise. There's normally an attribute "regulation" applied to the transformer that describes the difference from full load to off load - typically 5-10%, which looks to be the sort of zone that you're looking at here. Reading AirLinks's technical data sheet I can't find the regulation value (though I clearly struggle with their site), although they identify the attribute, and strangely relate it to efficiency which is a new one on me (they're kind of right, but the actual attribute of regulation is in the context of change-of-voltage).
Others here will (rightly, in my eyes) present a cautious (but reliable) approach to all this and recommend a 10% headroom on supply voltage to rated voltage. For a drive with 70VAC max input this is likely to result in a recommendation of 60VAC. Even that's a bit simplistic but it's a useful rule-of-thumb. So lets have a think about where you are now (no-man's land).
Firstly, what you know is what your meter is telling you. That's probably +/-1% or so, and realistically on a cheap meter (just making a blind assumption here) which isn't calibrated and on an AC supply that's probably going to give you +/-2V uncertainty on the display.
Next you're going to have an issue with line regulation. The UK grid used to be 240VAC (domestic), it's currently around 230VAC (-6%/+10%) trying to get to a EU standard of 220VAC (-10%/+6%). Your transformer is likely rated with primaries at 220VAC. If the mains is at 230VAC then you have a 5% uplift on the primary voltage - which will translate to a 5% uplift on the secondary voltage. That's also about where you find your measured secondary. Worryingly the mains supply can rise a fair bit above this - if you're sited close to a big transformer (e.g. on an industrial estate) you might find the supply around the 250VAC mark, with an appropriate rise in terminal voltage on the secondaries.
So, in a nutshell, you're likely to be at or slightly above the rated voltage of the drivers. And you have to figure on this before you consider any load from the drivers on the transformer. And, in an e-stop situation the load from the drivers is likely negligible, so you should design with this open-circuit terminal voltage in mind. I am a bit surprised that your build has got to this stage without attracting some concern from this thread.
Now, I don't know where to start with the driver. Quickly looking back I thought you was looking at LCDA86's - but one of your diagrams shows a LCDA86H - I think that 'H' is significant here as it raises the operating voltage and introduces a AC-supply option to what was previously a DC supply-only, and at a higher voltage. Clearly the non-H variant would require you to rectify the supply and you'd be so far beyond the rating I'd expect you to blow the drivers. If you do have the 'H' variants, then I think you're on the ragged edge.
You might, on paper, be in spec, but only just. You might also be conscious of supply line regulation and want to consider a little head room between the transformer output voltage and the max input voltage of the driver. You might (I would) also squint at the max rating of the driver and wonder if the designer built in some spare float in the electrical design - but the accountants usually engineer that out. Clearly I'm uncomfortable at the voltages (and power!) that you're playing with. It will probably work, but you might expect that the driver to be running to the limit of what it can, and you might find that the life of the driver is compromised, or, that it lets the magic smoke out when you first apply power, or that it runs fine until the end of time. The problem is you're essentially on/outside of the specification of the device and all bets are off.
Personally I'd probably risk it if I could afford to replace the drivers if needed. But, that's a personal (and some would say foolish) choice.
Ideally I'd have chosen a transformer closer to 55VAC secondary and give myself plenty of headroom.
Other than swapping components (drivers or transformer) for others, is there anything you can cheaply do?... not easily - you are looking to drop the terminal voltage without dissipating huge power (heat).
You could add a couple of bridge rectifiers on the secondaries, in series - rely on the non-linear behaviour of the diodes to introduce a typical drop of a couple of volts per device, and throw them onto the cabinet to passively cool them. At full chat these would dissipate about 20W each - not insignificant, but they would provide better regulation than a chunky resistor. The first thing that the driver would do internally is rectify and smooth the supply - all you're doing is adding a pre-rectifier rectifier... it'd work but it's not elegant.
In theory, you could remove a number of windings from the transformer. I wouldn't touch this solution myself - if only for the buggeration involved with this.
Beyond that you're talking serious solutions that would add cost, weight and power. Nothing springs to mind that provides an elegant solution.
Are you beyond the point of returning and swapping the transformer? If not, I'd give that a shot. Next I'd look to sell/swap on the transformer as near-new here, you might be lucky. Or, you can risk it. You might be lucky.
EDIT:
Going back to where I came into this thread... you could always short out the mounting bolt on the toroidal... I hear that puts a bit of a load on the transformer :cower:
I'll get my coat.
There's another option with transformer design. You could wind maybe 10 - 20 turns of 13A-rated (min) insulated flex in the opposite direction onto the transformer per secondary, and feed this in series with each secondary. If in phase it'll add a few volts, or if you swap the phase it'll reduce by a few volts (you'll not be able to tell the phasing - just try either way to wire them and measure to work it out). I'm not advocating this, nor will I do the experiment to prove it. It'd introduce additional losses (power) into the transformer but if you was in a corner it might offer a solution.
First off, looks like some great progress in the photos, well done!Quote:
Originally Posted by CNCRY
Regards the by hand - quite a few of us have used this method to good results. Yes, sometimes you cock it up, but just be slow and methodical double checking measurements.
No idea of your experience so lets ensure we hit all bases; make sure to centre punch well (optical if possible - the press type I also like), and let the drill bit align to that punch mark (if you clamp too tightly aligned slightly off, the bit won't happily sit in the punch crater). Use the drill press as much as possible (but check its square to the plate in both directions). If you're not using printouts, use marking dye. Set your digital calipers to the value from a reference surface, lock them off, then use them to scribe the line. When using a steel rule, never use the end for final marking (its a bit variable), always align to markings on both sides (e.g. to measure 10cm I'd align the 1cm mark and the 11cm.) - Now check using the end on the first mark!
If you come to fit components together and the holes are a bit out, you can always identify troublesome ones and widen only those. An M5 clearance hole already gives you 0.5mm of wiggle room, a 6mm hole isn't going to be the end of the world. Worst case is you have to make it again (oh no!) or remake it using the CNC later.
Regards accuracy - mostly to do with how you align the linear rails and screws. Use a dial gauge and get everything running smoothly and true to a reference surface. In your case this is mostly on ali extrusion or cast ali plate, so the height of the rail shouldn't be a massive issue - shim slightly if required, and you'll have plenty of left-right wiggle on the extrusion T slot. Your main problem will be aligning the two sides of the long axis so the rails sit at the same height. You won't go too far wrong if things move smoothly. Avoid software corrections as much as possible - the main one is the steps-per-unit, which shouldn't be too far from the calculated value (if it is very different, somethings probably lose).
Quote:
Originally Posted by Doddy
As far as I know there as never been an "S" version of this drive. I think you may be confusing these with the AM882S which did have an AC "H" version. These drives take both AC or DC.
Now your right on the edge with the voltage so your incoming supply must be on the high side. These drives will run at that voltage and won't give you any trouble provided your incoming supply doesn't fluctuate. The drives do have over-voltage protection, so they should protect them selfs from slight peaks and you will probably get a drop when under load. Only you know your incoming supply so only you can evaluate the risk.
The other option if you don't want to risk it is to throw a bridge rectifier and some Caps on it and go with DC.
If it helps you decide all I can say is I've run these drives at the ragged edge on volts before (I live next to the transformer and my supply can hit 256Vac so my supply is like a box of chocolates.!) without any troubles but I've also blown one of the smaller 50v versions by accidentally pushing too far so they only protect upto a point.!
Or buy a lower-rated supply that suits your incoming supply better. ( If it helps I'll take that one from you )
Yeah, was referring to the drive without alpha postfix - the stock LCDA86 - that has a much lower (and DC only) operating voltage. Take your point on the 'H' version.
Don't stress over it and it's perfectly possible to build an accurate machine that will easily cut the Aztec calendar by using hand tools, most of the builds on this forum are built solely using hand tools or a large percentage.Quote:
Originally Posted by CNCRY
Accuracy comes from the setting up and alignment etc. Remember Adjustment, Adjustment Adjustment so slightly oversize holes can help here.
Thanks everyone for the replies , no way I'd get throug h the build without the help here !
So I think the best option is going to be new transformer, with the cost of the drives at risk, and fact I'd prefer the simplest approach !
So to be 100% here, 60v or 55v to be safer if supply varies to high side . Will I lose much power @ 55V? And stick with 750VA?
Will PM you about other transformer if interested jazz.
Personally I would go with 60V and 625Va or even 500VaQuote:
Originally Posted by CNCRY
Watching thread with interest, as admire how you have got stuck in and learning as you go. I am trying to get a clear plan and design before spending a penny......so happy to learn from your journey.
No help on electricals, but back to printer paper plans. I use this all the time for woodworking templates. You want a spray can of 3M '77' good for temporary and permanent bonding light weight materials.
Keep going and keep sharing gotchas!
As I understand it (and I might misunderstand the theory) you're not losing power, as such, but top-end speed/torque. But listen to Clive.Quote:
Originally Posted by CNCRY
Gantry Sides done - need to counterbore the M12 bolts slightly but waiting on a 13mm drillbit for clearance hole..
Attachment 27880
Ended up ordering a new 60V output transformer. Fingers crossed I'll also have the closed-loop steppers and drives turning up in next few days. :)
Lichuan 5.5Nm - LCDA86H+LC60H2127 > https://www.aliexpress.com/item/3279...44bf3421SaYv5O
I'm thinking about cable management, its probably been a bit of an afterthought so far, but I'm thinking having it in my hands will be easier to "visualise". From other post's I'm thinking something like https://www.ebay.co.uk/itm/R38-18mm-...K/163618534489 or will that be underkill?
I'd have 2 x 8mm coolant pipes (and 1 air TBC), 1.5mm CY for spindle, Z and Y motors, encoder cable? Y and Z limits.
Also trying to find the right pulleys for Y and Z - planning on 15mm HTD5 (10mm bore) in 1:1 ratio - but how many teeth do people go for?
Thanks Andrew - I researched lots before starting but I find its easier to get started and "fix" some variables in the design otherwise I was going round in circles thinking and changing ideas. Probably means I will have a few gotcha's but hoping not too many! the help on this forum is great also, and helping me get a machine built which was just a pipe dream 6 months ago.Quote:
Originally Posted by Andrewg
20T are what I find best, don't go less than 18 because it makes it difficult with the boss size and you don't have much left for the grub screws. Also, don't try boring them by just drilling on a drill press, they need to be drilled and reamed accurately. I suggest if you haven't got a lathe or a very very good drill press or Minimill then buy them already bored.Quote:
Originally Posted by CNCRY
Attachment 27930
The good news - I now have 4 closed loop steppers and drivers - The bad news is that means more questions:)
So the motors come with pre terminated wires - oddly a 2M motor and 3m encoder one. To extend the motor one I assume I just use CY cable ? The existing cable does not seem to be shielded.
But with most people using CY cable right from motor to cabinet, should I be cutting shorter and using a longer run of CY - or does the closed loop negate the need for shielding?
Same with the trial prox sensor I have, it's pre cabled with non shielded wire, so do people cut short and join?
Also before I ask the manufacturer - does it matter on the polarity the AC connections to the driver are - there are no marking or instructions on Phase / Neutral, assuming it won't matter ?
Ryan
I tend to cut the motor wires short and use shielded cable, but I have used them with the supplied cable and not had any problems. If it was me and you don't have any CY cable then I'd use it as is. You can always change it later if gives you trouble.Quote:
Originally Posted by CNCRY
The encoder cable is usually shielded so it won't give you any trouble.
Cut these short as possible and use shielded cable.Quote:
Originally Posted by CNCRY
Doesn't matter it's AC alternating current so it bounces both ways so no polarity.Quote:
Originally Posted by CNCRY
Have my AXBB-E on its way now, so almost all the components - except for the VFD and spindle which I'll leave until I have a moving machine .
I'll be trying to get UCCNC to control one motor so I at least know it can be done (by me:) ) Linking it up to the Laptop is probably the only part of the electronics I hope goes easily with IT background..!
So I'm planning to use CAT6 cable I have already for STEP/DIR - do I just use the individual cores still twisted and leave in shielding for the run to stepper?
Also - what's the best method to join the fixed motor wiring /limit switches to CY cable - just solder and heat shrink over the top? if the CY doesn't run right to the motor (only 1/3 or so) is there any point grounding the shield at cabinet end?
Assuming you mean between the AXBB-E and the motor driver rather than stepper, yes. Try to use differential signal connections if possible, one twisted pair for Step+ and step-, etc. Shield as much as possible, ground the shielding to the star ground in cab.Quote:
Originally Posted by CNCRY
That's what I did. Yes always useful to ground the shielding at the cabinet, otherwise it's just not doing much.Quote:
Originally Posted by CNCRY
Yep Andy - meant between the AXBB-E and driver!
Some more progress on the physical build - ballscrew covers are on and work as planned! and most of gantry done. Next is to tackle the motor mounts. Plan is to use the long 35mm shaft length to go through the mount without having to hand route out a pocket as others have.
I also managed to connect 4 steppers and get them moving via UCCNC with nothing going pop, so know electronics for movement in place.
Attachment 28066
Attachment 28067
Attachment 28068
Reading Jazz's post elsewhere I realise I may have been confusing the X and Y axis all this time.oops. So stranding directly in front of the machine, I was calling left to right movement across the gantry Y and front to back X. So I have configured the dual ballscrew axis as X in UCCNC,
Reconfigure is just in software so OK, but can someone confirm I have been wrong, and X should be right to left (as per graph axis) and Y is dual axis. Probably good to know for a CNC machine:)
I'm also worried about the stand/table, When you put a decent force in the middle of the ply it flexes perhaps a couple of mm.
Initially I just needed somewhere to build it and didn't put lots of thought into the stand, thinking the machine frame will maintain it's structure. It's a wooden bench with ply top, I can do a fair amount to strengthen it up but - is this going to be a major sticking point? I see plenty of "desktop" type commercial machines out there which I assume people just stick on a workbench etc?
Really don't want to start having to get a frame welded if I can help it ! Ideas?
Thanks
Axis labelling can be however you want.
The convention is:
Standing in front of machine (as you will actually be using it)
Left to right is X
Front to back is Y
Up and down is Z
So yes like a graph.
CAD and CAM software is based on / defaults to this convention, so easiest to follow it.
Some people get funny and insist that across the gantry must be Y. Or the longest axis must be X. They are wrong. It's about how you draw the design / do the CAM.
Like Pippin say's there is no wrong or right so long as the Controller and Cam match up. Otherwise it gets very confusing when watching the controller Vs machine movement. However the part will still cut correctly provided it doesn't hit the limits which often happens when people mix Axis and Cam up.
But to Answer your question then yes you did have it wrong way around to what is conventional, that being following the Cartesian coordinate system of X=Lft/Rht Y=For/Aft Z=Up/down
Looking good by the way, soon be making chips. then the trouble really starts...Lol
Great progress, hope you will let us follow you to completion. Having read a lot of build logs here, it is so disappointing when a promising build tails off so you never learn if the design and approach had any merit! There are 5 builders with finished machines in the Gallery Post from 15 pagesx20 DIY build logs, so that is less than 2% that actually complete their machine and stick around long enough to share. It gives me pause, but you are giving me hope!
Not to criticise, but to show I am listening to the grey beards here, and want to copy much you have done:
I understand the frequent suggestion of having the gantry (X) separate and adjustable from the Y linear bearings for squaring up etc. You clearly still have access to your Y linear bearing screws, so adjustment is still available. However would turning the thick Y linear bearing plate into two, with the lower fixed to the bearings and the upper fixed to the gantry and then bolt and pin them when XY aligned make things more modular and adjustable?
That's just because people don't bother to post in the gallery thread. Whilst sure, there is an attrition rate, the success rate is a LOT higher than 2% in the build logs. I suggest you look at the last page in each one, you'll get a much better idea where they're up to.Quote:
Originally Posted by Andrewg
I'm going to answer this Andrew because many won't realize the difference and why it's important, well maybe I should say easier rather than more important.! Ryan might not even realize this yet because it's the first machine he's built.Quote:
Originally Posted by Andrewg
The Biggest difference is that the 2 plate method doesn't affect the ball screw alignment to adjust the gantry square. However with the single-plate method when you adjust the gantry by loosening the bearing plate you apply a twisting motion on the ball-Nut because the ball-nut mount is attached to the gantry sides which also rotate with the gantry. This puts a bind on the ball-screw so it causes excess wear and lowers the speed.
This then means you have to make adjustments in some other area to bring the ball-screws perpendicular to the gantry sides and parallel to the rails. In a nutshell it's a right pain in the arse.!! . . . The twin plates take all this away.