JSR's workshop chronicles

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mrfoo
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Thu Mar 12, 2020 1:32 am

Nothing wrong with low tech at all. The only real problem with digital caliper DROs apart from the small readout (and that can be taken remote with a bit of work and an arduino) is refresh time; rather than emitting a quadrature signal in real time there's a sample output every x milliseconds, which means you can't realistically use it for any kind of CNC application. You also need to be aware that, although they output in increments of 1/100mm (about 5 tenths in imperial), they're only accurate to 2/100mm / about a thou. That may or may not matter to you.

You can buy pretty good and relatively low cost DRO kits from corona-virus-land based on the same tech. Try, for example, the Shahe store on aliexpress (while you're ordering your dial gauges), but realistically you're as well off buying a few cheap digital calipers and lopping parts off.

Ixnay on the lapping compound here, too.
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Thu Mar 12, 2020 10:06 am

Gippeto wrote:
Wed Mar 11, 2020 3:44 pm
It's attached to the ways of the lathe, the bar moves for and aft with the carriage due to the single magnet on the end...much like the one you linked, just with magnets.
Sweet! So... do you just butt it up to the ways to make sure it's parallel?
mrfoo wrote:
Thu Mar 12, 2020 1:32 am
The only real problem with digital caliper DROs apart from the small readout (and that can be taken remote with a bit of work and an arduino) is refresh time; rather than emitting a quadrature signal in real time there's a sample output every x milliseconds, which means you can't realistically use it for any kind of CNC application. You also need to be aware that, although they output in increments of 1/100mm (about 5 tenths in imperial), they're only accurate to 2/100mm / about a thou. That may or may not matter to you.
That's good enough accuracy for me and I have no plans for CNC.
You can buy pretty good and relatively low cost DRO kits from corona-virus-land based on the same tech. Try, for example, the Shahe store on aliexpress (while you're ordering your dial gauges), but realistically you're as well off buying a few cheap digital calipers and lopping parts off.
Wow, quick search and there's a whole world out there, and reasonably priced! Thanks!

Something like that perhaps?
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Thu Mar 12, 2020 10:40 am

jackssmirkingrevenge wrote:
Thu Mar 12, 2020 10:06 am

Sweet! So... do you just butt it up to the ways to make sure it's parallel?
Slap it on, eyeball it straight to the ways and get after it. If you look across one straight item at another, it's fairly easy to see relatively minor angles of "off kilter"....and I'm under no pretense that I'm holding +/-.0005" so it falls under "good nuff".

Those igauging scales can be had in several places...suggest shopping around a bit.

The conversation got me looking around...might have to loosen the wallet a little and up the game a touch...DHL shipping is FREE?? Odd...but welcome.

https://www.aliexpress.com/item/3284476 ... hweb201603_
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Thu Mar 12, 2020 11:17 am

Thanks for the help guys, this is one avenue I hadn't even thought about and made me feel a lot better about having a less than perfect compound slide.

Speaking of the latter, Busy Bee offered me a new leadscrew but it doesn't seem to be the issue, so I've ordered a whetstone so be able to smooth it out.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Fri Mar 13, 2020 1:54 am

I'd suggest here : https://shahe.aliexpress.com/store/grou ... 9028.1_4_0

Cheaper than the igouging stuff, and comes from a reputable supplier. You'll have to wait until the end of the coronavirus thing, in all probability.
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Fri Mar 13, 2020 4:38 am

Gippeto wrote:
Thu Mar 12, 2020 10:40 am
The conversation got me looking around...might have to loosen the wallet a little and up the game a touch...DHL shipping is FREE?? Odd...but welcome.

https://www.aliexpress.com/item/3284476 ... hweb201603_
Those are glass scales, very accurate up to their limits but bulky. The people I know doing "real" DROs on small machines are using magnetic scales with home-potted heads bought, generally, direct from Renishaw. The heads run ~$30-40 a piece, the scales around $50/metre, you need to bring your own housings, potting compound, cables and readout to the party but the result is far lower profile than any other solution, and an order of magnitude, maybe two, more accurate than the "digital caliper" solution. These are guys who are holding dimensions to the micron...

Here's an english language thread on doing exactly this : https://www.model-engineer.co.uk/forums ... ?th=142115

Watch out for that free DHL shipping, too. You *will* get hit for import duties, *and* DHL will ass-rape you with their handling charges too.
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Fri Mar 13, 2020 9:20 am

mrfoo wrote:
Fri Mar 13, 2020 4:38 am
The people I know doing "real" DROs on small machines are using magnetic scales with home-potted heads bought, generally, direct from Renishaw. The heads run ~$30-40 a piece, the scales around $50/metre, you need to bring your own housings, potting compound, cables and readout to the party but the result is far lower profile than any other solution, and an order of magnitude, maybe two, more accurate than the "digital caliper" solution. These are guys who are holding dimensions to the micron...

Here's an english language thread on doing exactly this : https://www.model-engineer.co.uk/forums ... ?th=142115
Very interesting! The result is great but more work than I would want to put into it, looking for something more plug-and-play.

I'm edging towards this style even though I'm not looking forward to drilling and tapping my new lathe... still, it's worth it just to give me metric measurements which is what I've been working with all my amateur machining life.

Or maybe I should just fork out a bit more for something more serious?

Image

I like the idea of plugging it into the wall instead of having to change batteries, as well as the single display.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Fri Mar 13, 2020 11:00 am

That's more than serious enough for any hobbyist who isn't doing, for example, watch parts. The majority of the more inexpensive glass scales are, IIRC, accurate to 5 microns. The only real issue is size; they are a bit "phat".

For metric work, it's possible, with a bit of trigonometry, to use your compound slide for metric advance on one axis or another. Let's assume that your slide lead screws advance 0.1" per turn...

If you want your infeed to be metric for cylindrical turning, what you do is set your compound to an angle such that one turn on the leadscrew, 2.54mm, moves the tool inwards radially 2mm, i.e the angle x such that cos(x) = 2/2.54. If you lock your cross slide, you can now get infeed of 2mm per turn of the compound.

Obviously, this only works for relatively small feeds, less of an issue with cylindrical infeed, but if you set up for metric longitudinal feed you may find yourself restricted. There's also the issue that, although you have a metric feed on one slide, it fucks your placement up on the other axis.

There's another option, of course. For lathes like the Myford, you can buy replacement leadscrews for the slides and tailstock that are metric /or/ imperial, allowing you to convert a machine from one system to the other. They generally come with new handwheels, too. I looked through the parts list for your lathe, it only lists one leadscrew per slide, so I guess that's not a direct option. If only you had access to a machine capable of turning cylindrical features on the sort of metric leadscrew blanks one can purchase online, all you'd need to do would be to make up new leadscrews and stick some labels on the existing dials.

That would only leave the apron feed in imperial, but even that can be modified to suit (and without changing the leadscrew), by adding a slow apron feed wheel with a 127 tooth gear in the chain. 127 is the smallest integer divisor of 254, which is 25.4 multiplied by 10. Not sure what your apron feed is, but if it was, say, 5" per turn, you could add a 127 tooth gear behind or replacing the existing handwheel, and feed it from a second handwheel driving a 20 tooth wheel to get, if my mental math is right, 2cm per turn of the second handwheel. That's a fairly major mod, of course.

I've even seen machines with a selectable drive train on the cross slide allowing one to use metric or imperial at the flick of a lever.
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Fri Mar 13, 2020 11:17 am

Digging into that link posted earlier...and taking off on tangents like MF'er lol. (Focus you fack! lol)
If only you had access to a machine capable of turning cylindrical features...
:lol: If only eh?

The machines are (I believe) made by Weise...conversion parts may be available from there if a fellow was really so inclined.

I believe the igauging type scales have an incremental error...that +/- .006" accuracy would be over the full travel. Accuracy over 6" would be more like .002"....something to check into. The newer igauging scales are claiming .001" accuracy.
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Fri Mar 13, 2020 1:45 pm

mrfoo wrote:
Fri Mar 13, 2020 11:00 am
If only you had access to a machine capable of turning cylindrical features on the sort of metric leadscrew blanks one can purchase online, all you'd need to do would be to make up new leadscrews and stick some labels on the existing dials.
Oh man I've been wanting one for ages :roll: :D

Seriously though, that's a lot of work compared to just installing a DRO.
The only real issue is size; they are a bit "phat".
Is that really an issue though? I can see that they are bulky but I don't think that should cause any problems.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Fri Mar 13, 2020 2:43 pm

I think the biggest issue is loosing some travel with the tail stock. It's a bit tight to adjust the cross slide gibs as well.

https://warcoblog.com/2016/10/05/how-to-fit-dro-lathe/

https://www.model-engineer.co.uk/forums ... p?th=87648
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Fri Mar 13, 2020 4:02 pm

jackssmirkingrevenge wrote:
Fri Mar 13, 2020 1:45 pm
Is that really an issue though?
Would be for me. 52mm high (sensor + scale) seems to be pretty much standard, and is more than half the 102mm centre height on my lathe. Wherever you put 'em (and you're really only got 2 choices), they're overhanging, interfering. Simply won't fit on my machine, which is a shame - the price is right, as they say.
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Sun Jul 19, 2020 6:54 am

Image

DRO galore! Finally received these things and can start thinking about mounting them.

Correct me if I am wrong but I believe the bars can be cut down to size without issue, yes?
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Sun Jul 19, 2020 1:59 pm

that is my understanding, yes.
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Sun Jul 19, 2020 2:21 pm

Those are beautiful.
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