PDA

View Full Version : BUILD LOG: my build



jonm
02-08-2009, 10:55 AM
683

684

685

supported rail and bearings , stepper motors arrived from zapp ( thanks gary) so i made up two carridges and mdf box (still to screw and glue ribs inside box) supported rail will be bolted to mdf box , box will be bolted to base . that gives me 200mm from base to carridge , should keep x and y axis close together

jonm
02-08-2009, 09:11 PM
686

687

built the gantry sides today

Lee Roberts
02-08-2009, 11:39 PM
looking good !

jonm
03-08-2009, 01:20 AM
hi kip
nothing wrong with agricultural take a tractor for example ... not the lamborghini of vehicles ... but it does what its supposed to do very well ....

think you should upgrade your bed:rofl:........

now

any ideas for securing 12mm lead screw without machining the ends
would this do 689

irving2008
03-08-2009, 08:39 AM
hi kip
nothing wrong with agricultural take a tractor for example ... not the lamborghini of vehicles ... but it does what its supposed to do very well ....

think you should upgrade your bed:rofl:........

now

any ideas for securing 12mm lead screw without machining the ends
would this do 689Are you using 12mm studding or 12x3trapezoidal? A 12mm ID bearing will sort of do, but the fit will be poor. Better to machine the ends down to 8 or 10mm for a good fit on a suitable bearing and thread them for a locking bolt. have you considered how you are going to manage end-float?

jonm
03-08-2009, 10:19 AM
thanks irvine

using 12 mm trapeziod .. would the 2 grub screws in the pillow block not hold the screw against any lateral movement .... can the bearing take axial load ,.. was looking for a way round this as i dont have a lathe

jonm
03-08-2009, 12:56 PM
692693

built basic gantry this morning , threaded rod will pass through gantry sides bolting it all together , will also be bolted down through carridge angle iron(bed frame)

irving2008
03-08-2009, 01:00 PM
thanks irvine

using 12 mm trapeziod .. would the 2 grub screws in the pillow block not hold the screw against any lateral movement .... can the bearing take axial load ,.. was looking for a way round this as i dont have a latheThose type of bearings are poor at axial load, they can handle some but are not good for locating the shaft axially, which is what is needed to minimise backlash. Somewhere you need thrust bearings to take the axial load or angular contact bearings (hard to get in small diameter ID).

jonm
03-08-2009, 03:32 PM
cheers kip
good idea have some spare trapezioid will give it a go
with the grinder

irving2008
03-08-2009, 05:18 PM
Oh I dunno...it depends what load you're applying. For instance...I'm using pairs of common or garden 15 ID 35 OD bearings on my mini-router....zero backlash and well within their capabilities....For machining metals....AB bearings only for me. Horses for courses Irving...after all the MDF router will fall apart before the bearings reach their limit :naughty:
Its not so much the bearings Kip, its the pillow block approach.. the way the bearing locates in the block doesnt give a positive position to the shaft. I'm sure it could be made to work for light cuts, but thats a fairly big router Jon's constructing so I'd assume he's got big plans for it ...



For machining try a drill and an angle grinder equipped with a flap disc in combination with a jig.

I accept no responsibility if you get whipped :D:eek: these are long lengths of TR12, going to need some bearing support on those just to stop the whip, and thats before you put any pressure on with the grinder...

Lee Roberts
03-08-2009, 05:36 PM
What is...Be specific...is it the agricultural appearance or the use of bed frame?


Both ! :toot:

irving2008
03-08-2009, 06:31 PM
I have no bearing location on mine.....the bearings sit against Al plate as they have no radial loads....a spacer in the middle and a belleville washer and a bolt glued in....Nice glue though ;)
I can't visualise this... picture needed...

John S
03-08-2009, 07:28 PM
or angular contact bearings (hard to get in small diameter ID).

Look for magneto bearings, they are the smaller versions of angular contact bearings

.

jonm
03-08-2009, 07:29 PM
694

695

696


hi guys
thanks for input ... fixed gantry to sides today, bottom runner in , all feels pretty rigid

jonm
04-08-2009, 07:40 PM
going to attempt to grind down screws to 8mm then use skate bearing .. with thrust bearing either side , on evilbay thrust bearings for 1.90 each

cant find angular contact bearings at 8mm, and magneto bearings are 6 each ....... i am after all scotsman

jonm
04-08-2009, 09:47 PM
never mind.. soon be time to iron last years xmas wrapping paper....
and tippex the cards..

jonm
07-08-2009, 05:18 PM
cheers kip
bag of bearings arrived from " gap bearings " today...
will feed three 12mm bearings on to trapeziod screw fix bearings down with these712 drill on one end , then attack with grinder... sounds so simple....... we will see

jonm
08-08-2009, 01:40 PM
722

723

worked a treat took the threads of with grinder ....last few mil with a file .......
threaded end for m8 nut

irving2008
08-08-2009, 09:28 PM
722

723

worked a treat took the threads of with grinder ....last few mil with a file .......
threaded end for m8 nutI am impressed Jon. How did you jig the grinder to control the attack?

jonm
08-08-2009, 10:45 PM
irving
done it free hand , went down with the grinder till just the very bottom of the threads were left, then set calipers to 8mm ( screw still turning with drill) and used file to take it down the rest .. checking with calipers took about a hour to do .... happy with the result
should eliminate endfloat with thrust bearings

tribbles
09-08-2009, 12:33 AM
That's quite impressive - I've tried that technique before (although only turning the ends of bolts), and I wasn't that successful.

Mind you, I was using an electric drill as a lathe held in one hand, and the other hand holding the grinder :smile: I was also not really after precision (just wanted a nice chamfer on the end - it wasn't very neat, but did its job).

jonm
09-08-2009, 01:47 AM
tribbles
i had the drill in a stand lying on its side and clamped to the bench, because the screw was held with bearings it was running true ... there was no whip in the screw

jonm
19-09-2009, 10:20 PM
been busy with work.. but found the time to to make a carridge for the gantry... made a mdf one to start...far to much flex so got out the mig pretty pleased with this one very ridgid

jonm
29-11-2009, 06:24 PM
hi
went to local recycling yard today with some rubbish
and found this alu 1200 its 180mm x 90mm
this section is about 1200mm long , the other lenght is 5 meters
long,
(i see a big alu framed router) the bonus is the 6 meters of rack
that was screwed to it, how do i determine the pitch of the rack

tribbles
29-11-2009, 06:36 PM
Umm - forgive me if I'm being a bit dumb - but with a ruler/micrometer?

jonm
29-11-2009, 06:51 PM
hi tribbles
been looking on the net and find rack classed as mod 1
mod 2.5 etc etc all with different pitches , where do i measure from
the crown to crown of the tooth, because pitch line was talked about
that was a line about halfway up the tooth

tribbles
29-11-2009, 07:52 PM
I would've thought that as long as you measure from the same point in the rack, then that's okay.

When I was looking at racks, I looked at the mod sizes, and then looked for rack that was equivalent to that size.

What's the size you have?

jonm
29-11-2009, 08:03 PM
hi tribbles
pitch from crown to crown 11mm , width at top of tooth 12mm, what is mod 1, mod 2.5 refering to

tribbles
29-11-2009, 08:14 PM
I'm not exactly sure what the mod setting is, but I think it's the ratio of the number of teeth to the diameter of the wheel.

I know that generally mod 1.0 means for a 60mm wheel, you get 60 teeth; for a 120mm wheel, it's 120 teeth.

So, mod 1.0 would have 3.14mm pitch (circumference = pi*dia, dia = 60, so 188.49 circumference. Divide by 60 gives pi).

If it's 11mm, then it's probably 10.995, or mod 3.5 (3.5*pi = 10.995).

Kn8
29-11-2009, 08:41 PM
Hi jonm have a look at http://www.khkgears.co.jp/en/gear_technology/pdf/module.pdf hopfully this will make it a but move clear.

Ivan.

jonm
29-11-2009, 08:45 PM
hi tribbles
i am looking at this page http://www.ondrives.com/commercial-gears-racks-mr-type-steel.html looking down the mod column it relates to the width of the rack, the pitch line is down from the top of the tooth so measured down there i could have mod 1.5 .... i think .... maybe .....well i am getting confused with this

tribbles
29-11-2009, 08:56 PM
Not sure why they've measured P based on the height, but that could be where they're measuring from (I am doing this from memory).

I've got some mod 1.0 rack in the garage - I'll go and measure it - it should tally with what they've got.

tribbles
29-11-2009, 09:07 PM
Just measured it - it's 3.15ish mm, so I'm willing to go with 3.14.

Looking at this page (which I'd been to earlier):

http://www.ondrives.com/precision-gears-precision-gear-racks-1-0-module-precision-spur-gear-racks.html

it sort of indicates that half the pitch is (pi * m / 2) - although the end marker isn't exactly where I would expect it.

ETA: Looking at Kn8's document - reference pitch is pi * m, which is what I thought it was all along.

tribbles
29-11-2009, 09:12 PM
The "P" is the reference pitch height - i.e. where you measure the pitch from.

jonm
29-11-2009, 09:19 PM
hi tribbles
will go and get the calipers to measure the rack

tribbles
29-11-2009, 10:02 PM
Just had a thought about the meaning of the "P" value - this is actually the height at which the pitch diameter would ride at.

So, if you had a 60mm diameter gear, and "P" was 10mm, then the centre of the gear would be 40mm from the base of the rack.

jonm
29-11-2009, 10:24 PM
hi tribbles
get 11mm pitch 3.1mm at the crown of the tooth
and rack is 12mm wide , i am still confused cant seem to find anything similar, unless im measuring at the wrong place

tribbles
29-11-2009, 11:00 PM
Going from crown to crown, then 11mm is near as damn it mod 3.5. However, I've not seen that many mod 3.5s.

This seems to indicate this company makes them: http://www.rushgears.com/Tech_Tools/geargages.php

I take it you didn't find any gears with it, did you...

jonm
29-11-2009, 11:20 PM
hi
tribbles yes you'r right it looks like mod 3.5
no, no gears with it im afraid
mod 3.5 looks hard to find

jonm
19-12-2009, 11:15 PM
1273

1274

1275

1276

v groove bearings arrived from ebay this morning, the t slots on the back of the beam just happen to be size for a 10mm bolt head...
the x and y are rock solid much better than my first mdf creation
apparently this ali beam came from a stenna stair lift 190mm x 90 no flex at all even after cutting out the middle section . screw will go through the middle of the beam , gives me 600mm on the y

new trend t4 coming from santa for spindle...

jonm
20-12-2009, 08:07 PM
this ali beam is becoming a source of many parts .... with the centre section cut out it makes a very sturdy motor mount

1278

1279


the skate bearing is in the mdf with another thrust bearing on the other side ... have some delrin may make a bearing block from that

Ross77
21-12-2009, 09:15 PM
Looking good, those beams look promising. I,ve got some similar ones that are also from a stair lift. Not sure I would of cut so much out of it tho. :eek:

I plan to mount the rails on the other side with the T-slots, why did you choose to mount them as you did?
It will be interesting to see how it performs, save me some R&D :beer:

jonm
21-12-2009, 10:01 PM
hi ross
even with the centre section cut out there is still no flex in the beam, also reduced the weight , it was very heavy... wall section is 6.5mm.
was intending to put a few 8mm threaded rods through from top to bottom , along the lenght, with 2 nuts inside and and 2 outside which would have held it rigid, also could have adjusted the preload on the bearings (as a adjustable spacer) but think its going to be ok. can always be added later

with the screw inside keeps the y axis and z axis very close , going to cut the centre section out of the z as well , to keep router as close to the y axis , to reduce cantilever

holidays start tomorrow so plenty time to rebuild

what type of rail are you going to use?

Ross77
21-12-2009, 10:51 PM
Hi Jon
Fair play on the weight issue :smile: It seems that when you modify stuff you have to compromise, the removed section will reduce its strengh and torsional stiffness but as you say the reduced weight and the fact you can bring the leadscrew closer will probably be more benificial.

I'm just cautious now after setting up my lathe, it a fair old chunk of steel but it dosnt take much for it to flex and cause poor surface finish. I suppose it depends on what you are using it for.

My machine will be bit of a monster (stength not size) cus I want it cut seasoned hardwood and Ali. the rails are THK HSR 35's on the X axis and HSR 25's for the Y and Z. 30mm ground ballscrews and 750oz servos. just need the time to build it. :whistling:

jonm
22-12-2009, 10:19 PM
ross
that certainly is a monster machine you'r planning , i am only using a trend t4 as a spindle , some sign making , engraving just light work , will keep a eye on your build when you start

to see how you apply the ally beam

Ross77
23-12-2009, 11:16 PM
Unfortunatly its no. 3 down the list of machines and in the mean time I've got to convert a barn.........

My beam is slightly different as it also has T-slots on the side, so yet another option. I'm just looking at section properties at the mo to see what will work the best, as an engineer I'm a bit anal when it comes to calcs :heehee:

I'm still interested to see how yours works. From what I've found about much smaller beams and the fairly light duty you need I dont think you will have any problems at all. look forward to the next installment

dickieto
23-12-2009, 11:31 PM
Hello i have similar alloy beam to yours found in my local scrappies got it for nothing:yahoo:true scotsman:heehee:(check out my thread if you want) any ideas what mines might be off of? any reason why you did not use rack and pinion system that was attached to alloy? i was thinking of using zero backlash pinion with rack,any idea what size motors i would need to move gantry 1200mm wide weight 14kilos
:beer: Tom

Ross77
24-12-2009, 12:02 AM
Hi Tom
Yes I did see your thead, I will post on there once I can make the pictures bigger. Reply on your thread but what lead/ballscrews are you using?. i think the main response to your question is power... Belt drive and rack & pinnion require high power motors and give a low resolution.

With regard to identifing the beam, mine was easy as the burnt out chair was next to it with Stanna written on it...........:smile:

jonm
24-12-2009, 01:17 AM
hi tom
the beam i have is from a stenna stairlift, found at the local tip
the reason i am not using the rack is i cant get pinions for it ,with (tribbles) help its mod 3.5 , which i cant find anywhere
also as ross said there are the problems with driving it , belts, some kind of gearing on the pulleys, to bring down resolution, more power needed

Swarfing
24-12-2009, 01:59 PM
Give HPC Gears a ring, they will be able to source or make what you need. 01246 268080 or www.hpcgears.com

jonm
31-12-2009, 12:44 AM
1296

1297

1298

1299

first cut with router tonight , sons name engraved on a piece of laminate flooring... may not sound much , but to me its bloody fantastic ... to stand and watch a machine you have built moving around cutting on its own ... no hands , a happy chappy

...now to make it better

tribbles
31-12-2009, 12:57 AM
Looks very good - always nice to see the machine move for the first time and do something useful!

jonm
31-12-2009, 01:18 AM
tribbles
never did find out any more about that rack contacted ondrives ltd they emailed me a drawing of a rack i filled in the dimensions and sent it back , that was over a month ago never heard back from them

Lee Roberts
31-12-2009, 08:04 AM
Congrats Jon!

:beer:

jonm
22-04-2010, 11:14 PM
hi
on my y axis i have been using 4 v groove bearings i bought on ebay
http://cgi.ebay.co.uk/V-Groove-CNC-Router-Vee-Linear-Guide-Bearings-x-4_W0QQitemZ260574907047QQcmdZViewItemQQptZLH_Defau ltDomain_3?hash=

i had a slight wobble at the cutter when cutting and tracked it down to the few mill play in these bearings , preloaded the bearings against the rail but could not eliminate the play, so today two 800mm supported rails and 4 bearings arrived from zapp, these are going to be a big improvement ....

who says scotsmen are mean , why buy proper rails when you can buy 4 v grooves for 26 .....