I would but I ran out of scrap bits of metal ;-)
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I would but I ran out of scrap bits of metal ;-)
Sent from my XT1072 using Tapatalk
Been a bit busy with other things lately but had time to fit my Christmas present to my Chester champion v20 mill. My good wife bought me a dro kit, saves me counting the turns when drilling [emoji55] http://uploads.tapatalk-cdn.com/2016...f5143443a9.jpghttp://uploads.tapatalk-cdn.com/2016...c0b65a33aa.jpg
Had a little play with it but still managed to drill some holes in the wrong position [emoji16] although they were correct to my drawing, I obviously didn't position them correctly in sketchup and I just blindly followed all the positions. It's not a biggy though as it won't be seen and I'll put it down to weight reduction [emoji106] . spot the deliberate mistake http://uploads.tapatalk-cdn.com/2016...c5c789ad07.jpg
Also I am thinking of buying these castors for my machine
http://www.ebay.co.uk/itm/331315782016
they are rated at 110kg each which should be more than capable of holding the weight of my machine which will come to about 200kg without any workpiece. They are total lock castors which means the wheels and swivels lock and they have rubber tyres.
I'm wondering if anyone else uses their machine on castors and if they have any problems like the machine skipping around?
Cheers, Charlie
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Loving the mill :D
perhaps once you have witnessed the machine dancing about without castors, you will be in a better position to decide whether you want them :?
Haha, yes I am expecting it to dance whether it's on castors or legs but I am thinking if I have it bolted or strapped to the floor it won't move. I am wondering if having it sat permanently on castors is a bad idea? I like the idea of being able to easily move the machine when needed and it also has the added benefit of raising the bed by about 130mm. It seems a bit low now I've built the frame.
Cheers, Charlie
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http://uploads.tapatalk-cdn.com/2016...6f1a8c2933.jpg
Can anyone tell me if its safe to take these carriage's off the rails to allow access to the bolts when I fix them to my machine, they all came on the rails and I don't want to take them off and find loads of ball bearings falling out?
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No, it isn't safe. DAMHIKTIJKOK.
My carriages came with little plastic slides that fill the hole as you slide the carriage off the rail - not sure if you could use a flat piece of plastic about the right size?
No no, need to slide them off onto something the same size/shape as the rail, some expanded polystyrene works if your careful.
.Me
Bugger, I was afraid of that, gonna have to try and find something the same shape then to slide them onto? Going to have to try and make a mock rail then, would wood be OK?
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Just had to google that to find out what you meant!!Quote:
Originally Posted by Neale
Flat piece of plastic or wood about 3mm thick same width as slot ball fit into with tapered edges will work best. Foam and sponge can let the balls fall out if rails arnt perfectly lined up and push on them wrong.
To be honest thou If those are TBI bearings, which they look like then I think they are held in with plastic cage and don't fall out. The tricky part is putting them back on because you can easily damage the plaistc cage if not careful. . . . Better to be safe than sorry so make.!
The branding on the bearings is PDF, I tried searching for them but couldn't find them online, I got them off Chai before everyone switched to fred! not to sure about the rails, a bit bowed and terrible looking grinding bounce along the profiled angles but they seem smooth enough when moving by hand with a bit of pressure on them. time will tell I suppose.
I'm having a right mare trying to machine the faces flat for mounting the rails, it seems I needed a bigger mill because even with the gibstrips adjusted the bed sags with the weight when moving to the extremes of the slideways causing a bowed face so I'm going to clamp it upright and mill with an end mill instead of the flycutter I was using. what this means though is I am more than likely going to have to Epoxy my steel rails cause they are even longer and heavier than the aluminium gantry.
Just put the bearings on my ballscrew for the gantry and gave it a spin, it's a bit bent, the runout on the ends near the bearings is about 0.001" but in the middle it's over 0.020", my DTI doesnt read any more than that but I estimate it to be about 0.030"/0,75mm. Now I can attempt to straighten it on my mill but before I do, What would be considered as a reasonable amount of runout please?
Cheers, Charlie
Obviously the ideal is zero or near but I've seen worse work perfectly fine. I'd just fit it before doing anything because I think you'll find the runout won't be noticable when attched to ballnut mount. If you have vibration then it's an easy thing to remove and straighten.Quote:
Originally Posted by CharlieRam
Cheers for the info, I will fit it as is for now then.
Charlie
Hi, I have a few questions about the BK12 bearing supports, I've tried two of the supplied ones so far and the both exhibit end float, so after searching the forums I have tried placing the bearings back to back, packed with grease and reassembled but I think I need to shim them, the problem is how do I know what to shim, the ID or OD and where can I buy the shims from?
Also when the ballscrew is pushed fully into the bearings, it doesnt spin freely even with the nut slackened off, I assume I should be able to give the ballscrew a spin and the momentum should keep it spinning for a while, It may be the seal because it occasionally spins with the ballscrew but I have tried pushing it in a bit and pushing it out but it makes no difference? Any advice or help greatly appreciated.
Thanks, Charlie
Edit just checking this is Back to Back?Attachment 17676
Hi Charlie, the pic shows them back to back, I've got mine shimmed on the OD (as you want the tightening to pull the inner races together and load the bearings slightly) and cut the shims out of ali cans (good source of 0.1mm thick shim material as well as providing refreshment!) with some sharp scissors for the OD and a stanley knife for the ID. Think I used 2 or 3 shims per BK support but can't remember now.
Best get some more beer in then! What about the rubber seal, should it be spinning with the ballscrew?
Cheers. Charlie
No it shouldn't be touching the seal.! . . . Sure you haven't lost the little spacer.?Quote:
Originally Posted by CharlieRam
Some times they can be different lengths so check this. I've also known them be too short has well thou so it may mean spacer or making another.
The spacer is the thin tube that fits in the rubber seal upto the bearing ID right? if so then they yes they are there, I will check if both sides are the same length and if not I will swap them over.
They're different lengths, well mine were!
Are all pieces there assembled like that?
Attachment 17688
So if the whole bearings are moving in the housing, then shim the OD of the bearings. If only the ID of the bearings are moving, then shim only the ID. When shimming, dont shim between them, but outside in both cases.
If not freely rotating, then something is not right. It must be something simple, so just check again
It's all there apart from the lock washer, do I need one?
https://youtu.be/9jVThNfMAM4Heres a little video of what I mean, if the screw is pushed upto the sleeve, the seal starts to spin. I'm wondering if the spacer O/D is catching on the seal and when it is butted upto the bearing face it is dragging it round? Also I'm still not sure how freely the screw should move, I was expecting it to spin a little like a roller skate bearing, it seems to have resistence even without tightening the nut. The spacers are different lengths but if I put them the other way round the outer one would be too short and be inside of the seal, the way they are now both sides protrude from the seals.
Any help and advice greatly appreciated.
Cheers, Charlie
Here's a pic of mine, the spacer goes beyond the seal to keep the face of the machined shoulder away from the seal.
http://uploads.tapatalk-cdn.com/2016...11406e1392.jpg
It's been a while so heres a little update.. been working on the Z axis and also repairing my mill in the meantime as I stripped the plastic gear on my Chester champion.
Attachment 18249
But it's not moving very freely, I have clocked the rails up within 0,01 and put it all together including the ballnut and tried to push it up the rails, I could just about move it but it didn't feel very nice, I took the plate off and greased the carriages, and tried the rails on there own. one felt lovely and smooth but the other felt notchy on one of the carriages. So I carefully removed the rail and it appears as though I have a ball bearing missing!
Attachment 18250
Would this cause a notchy/stiff feel in the carriage or have I got other problems? I measured one of the ball bearings and it was 3.98mm so am I right in assuming 4mm. This is the first time the rail has been off so it must of been missing when I got the rails and if it hadn't been for the notchy feel I wouldn't of taken it off so please no telling me off for removing it :-P
Cheers, Charlie
Hi Charlie
When you get the carriage cleaned and running smooth, bolt the rails to your Z plate with the carriages installed but not bolted to matting face, offer the carriage/rail assembly up to your other plate and check the matting face with feelers to see if both plates are flat, one or both of the plates might be twisted or something.
Regards
Mike
I've got to get the carriage running smooth first, I tried both carriages on each rail, one of the rails is perfect but on the other rail I have one notchy carriage, that is when i discovered what looks like a ball bearing missing, just wondering if anyone else has had a problem, I can buy some 4mm ball bearings and see if it makes a difference, it definitely doesn't feel right though.
PS. I did remove the rails from the Z axis to check I wasn't twisting it.
Could do with the exact size ball mate, shouldn't really round it to 4 mil like that.
What you using to measure it?
I'll have a look in a mo as I've got loads of different size ball bearings, can send you some if you want.
Pop a ball out of a good unit and use it to check the dodgy one, let us know :thumsup:
.Me
I used a mic, but only a quick check and I may of been a bit over on the pressure, I was more bothered about dropping it in the swarf! I will measure a good one tommorow and get back to you, cheers. Do you think having one ball missing could cause the notchy tight fit? I'm thinking about removing all the balls and giving it a good clean incase the missing ball is actually in bits causing the notchy feel. Good idea or not? It doesn't look too hard, just a bit time consuming.
OK nps.Quote:
Originally Posted by CharlieRam
Well yeah I would seems silly not to at this stage, like you say not difficult just a time thing, may as well do it now and rule it out then revisit.
I doubt it's a ball gone to bits in there, more likely to be something else got in, check the returns and any paths the balls take for damage, lumps and bumps things like that.
I just rebuilt two ball nuts for someone and on one of the nuts, a plastic return was just a little bit snug as the balls passed through it, the symptoms where a slight judder/nock as the nut was spinning on the screw.
If you know what brand/make and model we may be able to look up the right size ball.
.Me
So I stripped the carriage, 119 ball bearings, measured quite a few of them and they were 3,975-3,988 ish so my measurement last night was good, still notchy :-(
Would the lack of one ball really cause this issue? degreased and checked all ball tracks, checked the end plastic things by pushing the balls back and forth and they seem ok? Could the plastic cage thing be chafing?
Just out of interest I got some digital kitchen scales on the end of each rail and pushed on it until the rails started to move, the good one started to move at about 400g of pressure, the notchy one was just over 1000g, for info the rails are 375mm long.
BTW, the brand is PDF and model is DFH20A
I also have a set of 600mm PDF 20mm profile rails, which dont run smooth at all. I will change them out with hiwin down the road when I get some leftover money to do so. For now Im gonna keep it as it is until it proves to be a huge problem.
I would think they are to the closest standard size of 5/32in then, your in luck as well because I've got some that size, PM me if you want me to send you some, call it the postage cost...Quote:
Originally Posted by CharlieRam
Lee
Lee Roberts is sending me some ball bearings, I'll see if it makes a difference and if not I will fettle the carriage a little......Now wheres that bastard file ;-)Quote:
Originally Posted by sinnsvak
Good Luck! It may be, and I sincerely hope so, that the smoothness will show up after a couple of hours use.
Well that's been a few days of discovery I won't forget in a hurry!
I stripped the carriage again, gave it a good clean and scotchbrite on all ports and ball ways, reassembled the carriage temporarily, put it back on the rail and started to slide it up and down to check the tightness and then....the end came off and 120 balls all over the floor! F$%k, I found 118 of them and still had 2 spare from Lee luckily.
Oh yeah, I also decided to check the other carriages now I'm confident the balls wont go flying if I remove them :stupid: a couple of the others seem to have one ball missing too!
Cleaned it all again and secured it properly this time but it still felt tight, that is when I noticed the carriages looked slightly different on the exterior, so I checked the serial numbers again, both are DFH20A but the nice fitting ones have S01411040 and the tight one has S01207841. Does anyone know if any of these numbers signify the preload, I'm thinking I may have a higher preload carriage or is it just a batch number and one was made at a different time with not such a good QC?
More Importantly, will it affect the build having a mis matched carriage?
Cheers, Charlie
Hi Lee,
Cant help there sorry, what you could do is mic the ball's and see if they are diffrent, this may give you the anwser.Quote:
Originally Posted by CharlieRam
I can’t see it being a problem, so would just go with it, others may know better but I can’t think what problems it may introduce, ultimately if it is a preload difference then its unbalanced but would suggest it’s going to be such a small amount, just leaving you with the least amount of preload as your best number, so again not a problem.Quote:
Originally Posted by CharlieRam
.Me
Is that how the preload is set then? with slightly larger ball's?Quote:
Originally Posted by Lee Roberts
Hiya,Quote:
Originally Posted by CharlieRam
Pretty much yes, if you use slightly bigger ball bearings than the distance between the carriages and rail.
The ball bearing size (relative) determines the amount of preload achieved. From what I've read, the most common amounts of preload used for linear guides are 8, 5 and 2 percent of their load rating (dynamic).
For ballscrews and nuts you can do the same thing with the ball sizing, use an adjustable nut or use two nuts.
.Me
Well.....I've been a bit quiet on here and for good reason, I found out my good wife was having an affair!! So dealing with a lot of shit at the minute, mainly custody of the kids and making sure I still have a family home and some cash left at the end of it. Just had my Decree nisi date for the 1st September so all being well and if we can come to a fair agreement on asset splitting (Fair to me would be she got F all but that ain't gonna happen) Hopefully I will be divorced middle of November, What a waste of 22 years! but onward and upward and hopefully I will be in the mood to start/finish my machine soon. Think I need a hobby to get me out the house and meet some new people.
Take care and if you feel like lifes getting you down....Just think about me and how it could be worse and have a good chuckle :) I know it's not quite life or death but sometimes it feels like it!