a Steel Box Section Build with SBR20 & Ballscrews Plus a few questions

[grain_r]

I hope I never upset you, If you offered me a drink i'd certainly think twice i'm trying to work out if you have a workshop or and evil genius lab.

[cropwell]

Yes Jazz - I know all this and more (chemistry at Uni), thats why I recommended the Wickes stuff. It will get the zinc off in about 15 to 20 minutes and is not as dangerous as more concentrated hydrochloric or sulphuric acid. I am not so sure about chip shop vinegar, acetic anhydride would do the job, but I certainly wouldn't want to inhale the vapours of that stuff.
I have been told that in Barnsley, the pigeons fly backwards to avoid getting the shit in their eyes. Is this true Dean ?

Happy Holiday.

Rob

[JAZZCNC]

I have been told that in Barnsley, the pigeons fly backwards to avoid getting the shit in their eyes. Is this true Dean ?

Ye along with we all wear Flat caps and have Whippits mi old Cock.!! . . . . n wi av r own X factor darn intarn called B factor n ter's latist winners..

[grain_r]

Hey all

Well I though I would pop a couple more pics on here as I'm doing bits to keep me motivated too. I'm having a tapping Issue for some reason at the moment. I have used a 4.2mm Cobalt drill bit and I have used a centre punch and then I have used the cobalt but it wanders I have then even turned the pillar drill by hand a few times and I was surprised but it did cut which I guess is because its a new drill bit and then started it and unfortunately it still wandered so I stopped it and put a little pressure on the work piece and then started the drill and that works better but still not good. I think My holes have then gone oval even when the wandering stops when in a decent start for the bit.

I'm thinking I might even get a better job done with a hand dewalt battery drill. Yes I know its a cheap drill but Would have thought it should drill holes but maybe its me.
I have even tried to use a stepped drill of 4mm and better rigidity but they are the worst with one side ok and the other only 1 thread

The Culprit



The Holes (Although it does screw in and hold when tightened but not right somewhere)



I have ordered a new tapered tap but wondering if the 3mm just isn't thick enough. Luckily On this bit I can put nuts on them but won't be able to weld them on.

Oh Well I will carry on.

[JAZZCNC]

Then You need a spot centre drill bit to start the holes.

[Lee Roberts]

Typically you would spot drill the hole first with a spotting drill bit (like a normal bit but shorter and so stiffer) or a center drill bit, a smaller diameter drill bit maybe used as/or well, just take your time as they snap easily at those sizes.

I can't see this would be a problem with your bench drill though, would continue to use it instead of going free hand personally.

.Me

Edit: Not sure if you've settled on a Z Axis design yet but here is a link to how I've done mine using 20mm plate and TBR16 round rails:

Link: http://www.mycncuk.com/album.php?albumid=387

[grain_r]

Hey Everyone

I have been working Away at the base still and we have a new baby Daughter arrived too. So not too much work been done.

But the internet is a cruel master I have been looking at all of the threads and it seems like Hiwin is the way to go and sell the Supported SBR20 Rails ?

I have been looking at the 20mm and 25mm but I'm unsure if the bigger is better rule applies on this. I am just thinking that once all of the holes are in the nice new steel and the aluminium it will be best to swap now especially how long it takes me to do anything.

I think my design will still be good for the rails instead of any changes I have had a look at chai's site on Ali Express but seems more expensive than others but is Hiwin the same from everyone and they are just suppliers or are there differences in the quality of these things.

Thanks everyone.

Rob

[Colin Barron]

Were there no cheap scrap accurate machines that could have been rebuilt.

[grain_r]

Were there no cheap scrap accurate machines that could have been rebuilt.

Hello Colin I think that if something comes from your head and you build it you achieve knowledge if nothing else.

I have bought unfinished projects for other things before in life and they are rarely a simpler and cost effective way of doing things and normally a compromise in design and quality.

That said I imagine there are some very good machines out there that have started life as another machine.

The build is taking quite a while to get the frame finished but I'm certainly enjoying every second of the process.

Thanks

Rob

[Colin Barron]

A very small drill bit can be used to find the centre spot made with centre punch,(spindle not moving), work should be clamped lightly but adjustable, clamp the work tight when positioned and check again to confirm it has not moved. Drill a small hole to confirm position then full size. A smaller drill bit will not move off centre as much as final size. If you still have problems use a centre finder (point) as shown here. https://www.youtube.com/watch?v=RhtBdar4iVg . I was informed as an apprentice many years ago that using the pointer method an accuracy of 1/64th inch (0.4mm) is achievable.