I have counterbored m12s into 20mm plate. The 8mm left between the head and the extrusion is plenty enough.
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I have counterbored m12s into 20mm plate. The 8mm left between the head and the extrusion is plenty enough.
I think that looks like the best solution. There 20mm so 8.4mm thickness left according to solidworks. Now the question is, do I attempt to drill them out and re-bore myself or send them back and get them re-done professionally? I'm worried about the drill bit wandering off from centre.
Attachment 17511
Well that's up to you! My build has been decidedly diy so I'd have to do it myself! I would have thought the bit would find its centre in the existing hole...Quote:
Originally Posted by biketrialsdave
Attachment 17512 these were drilled out with several bits starting small and working up...... You would just be starting further down this process?
They look very good! I assume you used a drill press? (mine is an el cheapo one and has a bit of play in the head). Did you use any kind of guide for the bit?
No, no guide and my press is only a table top Axminster thing so nothing pro! Attachment 17513
Minor detail not worth stressing over. Domed head look fine without being counter bored so don't bother just drill them out to 12mm.Quote:
Originally Posted by biketrialsdave
Attachment 17515
Wow Jazzy! Pimp my ride eh?!
Fair point but I have to say counterboring is strangely pleasurable!!
Bling Bling.!!!!Quote:
Originally Posted by JoeHarris
Normally I do counter bore Joe because it's even easier when Cnc machine does it for you but In this case budget was tight and machine is small so 15mm plate was used so not much room to play with and it's only cosmetic anyway so no matter.!
Also - if you counterbore you could cap the holes with diamonds to complete the look!!
I was wondering if a step drill (13mm max diameter) would be a better idea for enlarging as it would be self centering?
Step drills are intended more for sheet metal. I would get a decent hss twist bit. You can pick up dormer bits on eBay for very little. http://www.ebay.co.uk/ulk/itm/140928964799Quote:
Originally Posted by biketrialsdave
I think you'll be fine, what may happen is you get chatter from the drill so may end up with the not so perfect edge.
Also you don't really need to buy proper counter bores, the right size drill bit used in the same way works great for pretty much the same effect, do you really need need flat bottom holes for the cap head to live in?
The timing is good on this one because I'm currently in the process of doing the same myself, stepping up in size, cheap drill press, simular sizes being dealt with, here's some pics:
http://uploads.tapatalk-cdn.com/2016...86068b05ad.jpg
http://uploads.tapatalk-cdn.com/2016...70c31fa3bf.jpg
http://uploads.tapatalk-cdn.com/2016...c0fd0c129a.jpg
I'm stepping up to 15.5 and 20mm for the screw clearance hole (the very middle one) :). I can show the bigger holes if you really want but they came out pretty decent, don't use a step drill and if you don't mind go for quality drill bits.
If you do end up with a less desirable finish on the bore OD, you can always add a chamfer with a counter sink or again an over sized drill bit.
http://uploads.tapatalk-cdn.com/2016...b5690b89f0.jpg
Edit: Just to add, I prefer to go with Dormer for drills and taps after using them after cheap crap and the difference is night and day, however even on eBay Dormer comes at a price, check out Osborn/Warwick/Heller/Goliath, look up Steve (cncpoorboy) on eBay he's got some smashing deals for what what looks to be old new stock, new stock and the stock is all those shiny metal things we're so attracted to.
.Me
An m12 counterbore will cost the same if not less than the equivalent bit, so I would do the job properly... http://www.arceurotrade.co.uk/Catalo...k-Counterbores
I've added an edit Joe...Quote:
Originally Posted by JoeHarris
Define properly, plus a counterbore only dose one job, a drill offers you more options/value if you don't mind being a little creative with it.
Not getting into right or wrong as I think it's pretty obvious and such a simplistic thing being discussed, just saying what I did/do for these things.
.Me
Fair enough! I guess you always have a choice whether to go Heath Robinson or cough up for the tool which has been designed for the job. It's no big deal. I've been milling aluminium with a router because I can't afford a mill! It depends where you draw the line. I have just developed an irrational love of counterbores since buying a set recently and want to spread the joy!!
Which set did you buy? There actually seems to be quite a variation in counterbore sizes which I find odd. Some that don't even fall under the category of normal or close fit...I wonder if the dimensions are just rounded on some websites...Quote:
Originally Posted by JoeHarris
Yes I found that. I bought my m12 from arc euro and a set of Ruko m3-m10 on eBay but only because I spotted a good deal, can be quite pricy otherwise.
Think I have the bolt problem sorted now...will update soon. Now on to the next problem...
I was playing with my ball...screws last night before bed ;) I've noticed that the Z-axis ballnut (RM1605-C7) seems a little notchy and not smooth. As if there could be some swarf or something inside? The ballscrews are covered in a light machine oil (I assume to prevent oxidisation). Do I needto strip down and clean everything before use? Do the ballnuts require greasing first?
On a similar note, is there any specific preparation I need to do to my linear rails/bearings before use? (I need to assemble the HIWIN ones).
Cheers,
Dave
On my HiWin, I followed the manual, I used light grease and worked it in slowly by running the carriage up and down by hand and giving a little grease each time, this is done on the rail of course ;)
Hi all,
More progress has been made and my bank account is starting to hurt! I sorted the bolt problem, counter-bored the plate for M10 socket caps and then heli-coiled the extrusion to match.
I am taking photos as I go so I think I will do a big dump of information in one go rather than little updates every so often.
I have started to really think more about swarf and coolant removal during/after machining. Hopefully the paint diagram below will help explain what I'm thinking about doing. The gap will allow me to brush swarf straight off and into a bucket under the bench. Would the proposed design weaken the frame too much?
Attachment 17605
EDIT: Infact, could I even remove that extrusion completely or is it going to put too much outwards pressure on the sides?
Attachment 17606
Very productive day today.
Sneaky peak...
Attachment 17617Attachment 17618Attachment 17619Attachment 17620Attachment 17621
Looking good!
Coming along nicely keep up the good work you are getting there:yahoo:
Looking good Dave keep it rolling mate. .:applouse:
Nice work Dave. Don't tell me you didn't enjoy that counterboring?!
It was very satisfying. Made a big mess though!
Getting there slowly!
Attachment 17636Attachment 17637Attachment 17638Attachment 17639
Like eating an Elephant Dave.? . . .Small bites at time then before you know it your eating desert. . :triumphant:Quote:
Originally Posted by biketrialsdave
And desert is the electronics?!
Haha, well that's my day job so fingers crossed that will go OK! Been having thoughts of designing a BOB but need to not get side tracked!...Quote:
Originally Posted by JoeHarris
No frame is the Meat. Electronics are the Veg and Chocolate Chips are the desert.!!Quote:
Originally Posted by JoeHarris
Dave don't try to reinvent the wheel it's not worth the effort.!
Nice work Dave. Solid design and well made. You will be rewarded soon . . .
lmao! ;-)Quote:
Originally Posted by JoeHarris
.Me
I'm getting there! Will do a full write up at the end (if there is such a thing! ).
I need some help if I may. On the x axis (long axis) when the gantry approaches either end of the bed, the ballscrew gets tighter. It's not just one side, happens to both. Something must be bowed?Attachment 17912Attachment 17913Attachment 17914
And could anyone explain what tramming is please?
If the ballscrews are bent then you will get a periodic tightening as you rotate it, especially at either end of travel.
If the ballscrews / mounts / nuts are all mis-aligned then it will have a constant tightening at either / both ends.
Assuming the ballscrew is fairly straight then looking at the design the ballscrew supports and ballnut bracket are probably not completely in line. It doesn't look like you can adjust in the plane away from the sides of the machine, only up and down.
Try moving the machine to the driven end, loosen the 6 bolts holding the ballnut to the ballnut bracket, and remove the floating end bearing. This should allow the ballnut to sit in an unloaded position.
Nip the bolts back up and move the gantry over to the other end. Gently slide the floating bearing back on - it should sit snug onto the mounting block on the side of the gantry. If it is out, fit a shim. If it is tight you need to machine a bit off the mounting block.
Tramming is related to getting the spindle motor normal to the bed so that the side of the cuts are 90deg to the top surface. You can get close by putting a bar in the spindle and using an engineers square to check the spindle is 90deg to the surface on all sides / angles. You can also get a twin DTI block which gives a much better indication of tram condition. Have a read . . .
http://www.cnccookbook.com/CCMillTramming.html
I think I've solved the ballscrew problem, re-made one of the BF mounting blocks and shimmed it a little. How hard should it be to push the gantry back and forth on the machine? It takes quite a lot of force to get it going then it still requires a far amount of force to push it...
The mechanical build is nearly complete, just got the back gantry cover to finish!
Attachment 17963Attachment 17964Attachment 17965
My one slides fairly easy with the belts off.
Did you try loosening the bolts on the BK & BF then moving the motion to the bK end and nipping them up then move to opposite end and nip the bolts up - there should be no tension on the screw when the bolts pull up.
This worked wonders on my build.
If you mean with the ballnuts disconnected from the gantry then the gantry should move with one finger. A light shove should see it carry on for a bit and coast to a halt.Quote:
Originally Posted by biketrialsdave
If it is hard to move and stops as soon as you stop pushing then either bearings are faulty (unlikely if new) or more likely is they are misaligned relative to each other.
They are very intolerant of misalignment in any plane. This is why epoxy is popular. One side could be higher than the other side, or they could be the same height but twisted, or they could not be parallel etc. etc. I does not take much to make them bind.
Did you set the first rail against a known straight edge?
Did you then use a DTI to set the other rail parallel to it?
Are they at the same level as each other (use straight edge across bearings and check with feeler gauge)
Loosen the bolts connecting the gantry to the bearings on one side, then see if it improves. If it does you have misalignment.
Time spent getting this smooth will pay dividends in the long run.