Author Topic: worn out half nuts  (Read 429 times)

savarin

Re: worn out half nuts
« Reply #15 on: November 17, 2018, 09:14:50 PM »
I would love to make my own but they are a complex shape.Once I'm up and running I may consider having a go.They need a steel pin cast in situ and some machining so if its possible it will be worth while but would having spares on hand mean I wont be so carefull of damaging them?I'm hoping the new ones will arrive by the end of the week. Someone in the US is sending them to me, thanks a million hman.
All the oil grooves are cut, all the oilers are installed, new gib screws are in, all reassembled and adjusted and I cannot believe how smooth it all is now.I added an extra saw cut on the cross slide nut so the adjusting grub screw actually does something and the backlash is down from around 2mm to approx .25mm but there is definitely wear in the screw as the backlash changes depending upon where in its travel it sits. (all feel, no actual measurement) I hope to make a longer cross slide lead screw once its all working as it should and extend the cross slide travel and also add ball races to it for smoother movement.
I've solved the lead screw moving towards the bed.Loosen the apron bolts, lock the half nuts to the lead screw, then tighten the apron bolts and voila perfect alignment.Its surprising how much the apron can be moved in twist and in/out.

savarin

Re: worn out half nuts
« Reply #16 on: November 25, 2018, 07:51:36 AM »
Once you start fettling you just cant stop.
I've decided to extend the cross slide travel and rather than stop there its going to be a new lead screw M10x1, two ball races, larger dials and handle.
I have a length of alloy 60 x 100 mm long so that will be the bracket, the handle I've turned from a zinc alloy ingot.
I made a 100 segment circle scale held in the end of the spindle as an indexing aid to scribe the 0.01mm divisions.
The saddle stop is clamped with a "G" clamp.
Once I finished the divisions I knurled the end, then bored the middle out with a hole saw then parted it off.
The last pic is the finished dial sans numbers sitting on the handle with a very smooth fit.
The bearing on top will be in the extended bracket.
I know this flexi lathe cant hold this kind of accuracy but I though with the 1mm thread and 100 divisions on the lead screw it will make the length calculations easier (I hope).I'm uncertain what material to use for the lead screw.
I have enough stainless I could use but am unsure if it will wear ok.
The nut will be either brass or some cast bronze if I melt it.

savarin

Re: worn out half nuts
« Reply #17 on: December 01, 2018, 07:10:56 AM »
Started on the support bracket, I hate it when the strings just wrap around everything, Scary stuff.
the parts have arrived so its geterbackproper.
 I took a lot of care getting everything adjusted to as spot on as I could and ensuring the half nuts closed from both sides equally took a bit of fiddling but we got there.
 Next I added the brass brush John sent, so simple, so effective, I love it and with the cross slide shield I think swarf will find it very difficult getting in there.
Does it all work now?
 Yep
 single point M8 x 1 in stainless.
 These are for the bearing clamps on the binocular.


Carpenter84

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Re: worn out half nuts
« Reply #18 on: December 01, 2018, 03:16:36 PM »
Those look spectacular. I'm still amazed at your enginuity and creative thinking to create things with as little equipment as possible.
I very much like the knurling, and the finish on the parts looks great.
Shawn

First 9x42 column mill,
Enterprise 10x28 lathe,
Ko Lee 6x12 surface grinder,
Airco dip/stick 160 welder,
Fully stocked wood shop.

savarin

Re: worn out half nuts
« Reply #19 on: December 04, 2018, 03:01:15 AM »
Thanks Shawn much appreciated.


I've started on the cross slide shaft but its a long process turning that down from 16mm to 10mm.
However, like all my projects I've been side tracked again.

I'm attempting to make a vernier scale, no real reason in this instance just to see if I can.
The idea is to add a vernier scale to the cross slide dial of my lathe.
On a flexi 9x20 its a bit of nonsense but what the hell.
I have engraved 100 divisions around the dial using a scale I printed off from this site.
http://www.cgtk.co.uk/metalwork/reference/divider  as you can see above.
This hopefully will give me an advance of 1/100 of a mm of cross slide travel per division so with the vernier theoretically it should advance 1/1000 mm. I'm thinking if I print off a scale with 90 divisions to the same diameter size as the 100 scale and use that to engrave another dial but just use 20 divisions this should give me 9 divisions in the space of 10 divisions on the original scale.
A quick test by printing both scales and overlaying them to see through the 90 to the 100 underneath seems to bear this out as with the zero on each scale in alignment the 9th division of the 90 scale sits on the 10 mark on the hundred scale.
or should it be a 110 scale where the number 10 sits on the 9 of the hundred scale.
Which one would be the correct version?

Am I on the right track here or just blowing bubbles?

chips and more

Re: worn out half nuts
« Reply #20 on: December 04, 2018, 09:04:33 AM »
Thanks Shawn much appreciated.


I've started on the cross slide shaft but its a long process turning that down from 16mm to 10mm.
However, like all my projects I've been side tracked again.

I'm attempting to make a vernier scale, no real reason in this instance just to see if I can.
The idea is to add a vernier scale to the cross slide dial of my lathe.
On a flexi 9x20 its a bit of nonsense but what the hell.
I have engraved 100 divisions around the dial using a scale I printed off from this site.
http://www.cgtk.co.uk/metalwork/reference/divider  as you can see above.
This hopefully will give me an advance of 1/100 of a mm of cross slide travel per division so with the vernier theoretically it should advance 1/1000 mm. I'm thinking if I print off a scale with 90 divisions to the same diameter size as the 100 scale and use that to engrave another dial but just use 20 divisions this should give me 9 divisions in the space of 10 divisions on the original scale.
A quick test by printing both scales and overlaying them to see through the 90 to the 100 underneath seems to bear this out as with the zero on each scale in alignment the 9th division of the 90 scale sits on the 10 mark on the hundred scale.
or should it be a 110 scale where the number 10 sits on the 9 of the hundred scale.
Which one would be the correct version?

Am I on the right track here or just blowing bubbles?

I think you should print a scale with 110 divisions. I just looked a vernier scale. The divisions are narrower on the vernier scale than the dial divisions. But Iím not sure on the how many divisions 110? or whatever?
« Last Edit: December 04, 2018, 09:09:28 AM by chips and more »

f350ca

Re: worn out half nuts
« Reply #21 on: December 04, 2018, 09:05:22 AM »
I made verniers for the angle measurements on a tool grinder I built. I remember the bloody things gave me a migraine trying to figure them out.
Think you have to work in degrees.
For the main scale with 100 divisions you have 360 degrees/ 100 div gives 3.6 degree/div.
10 divisions on the vernier should equal 9 on the main so 9 times 3.6 = 32.4 degrees for 10 divisions on the vernier
Now the vernier is 32.4 degree / 10 = 3.24 degrees /div.
For a full rotation the vernier scale has 360 / 3.24 or 111.1111111 divisions.
Is your brain starting to hurt ?
The 110 division scale would probably work with a 1 % error on the 10ths reading.


Greg

savarin

Re: worn out half nuts
« Reply #22 on: December 04, 2018, 06:51:54 PM »
I agree with the 110 scale. I will report back once I've engraved the dial.

savarin

Re: worn out half nuts
« Reply #23 on: December 05, 2018, 07:07:18 AM »
I eventually used the 110 segment scale, it gives 10 divisions in the space of 9 divisions on the main dial.
 Heres all the parts for the extension and the vernier engraved,
Its a nice smooth action with the two bearings.
 I'm really happy with the M10 x 1 mm thread, the longest I've cut and very smooth.
I have to mill off the excess aluminium from the extension bracket and I haven't worked out how I can hold it to do this job yet. I may have to visit a friend.
If you look closely you can see the brass shim where I over bored the bearing recess. Dork!

chips and more

Re: worn out half nuts
« Reply #24 on: December 05, 2018, 08:32:26 AM »
Can you bore out the bearing recess even bigger and make an aluminum sleeve? If done well the repair could be invisible and work just like one piece of metal.

savarin

Re: worn out half nuts
« Reply #25 on: December 05, 2018, 06:54:13 PM »
Can you bore out the bearing recess even bigger and make an aluminum sleeve? If done well the repair could be invisible and work just like one piece of metal.
I dont think there is sufficient room left as I have to mill down to the top of that scribed dovetail line.

savarin

Re: worn out half nuts
« Reply #26 on: December 09, 2018, 07:00:46 PM »
Started milling the waste material with an end mill but it was very rough finish.
So I ground a broken tap to a small raked flat tip cutter and used a small boring bar to remove the rest.
Now its being filed down for the final fit.
 Meanwhile -
 can anyone see a reason as to why I cannot cut a channel or drill a hole for the extended cross slide lead screw at the end of the cross slide so the nut can travel a bit further?
 Would a channel weaken the saddle too much?

chips and more

Re: worn out half nuts
« Reply #27 on: December 09, 2018, 08:07:45 PM »
Yes, I see what you mean. Tough call. I think I would leave it alone. Also removing material in that kind of area could release internal stresses and the thing could warp. If you still are going to do it. A hole would definitely be a better plan/idea than a channel.
« Last Edit: December 09, 2018, 08:10:12 PM by chips and more »