Craftex 7x8 Lathe

[Theclockworks]

First thing I would do is check the machne over every nut and bolt the guy that made mine must have had very sort spanners every thing need nipping up get a good quality chuck,change the jib strips and fit DRO,last I would fix in place once centerd the tailstock unless you're going to do any tapper turning with it. But most of all have fun they're capable little machines when sorted. P.S most come out of the same factory in different colours with numerous name badges

 

[Nitrous]

There is one BIG SERIOUS ISSUE
they dont take into consideration your back lach in your lathe.
these are quad encoder reader. They count the step going up and going down to the turning of your handel. So if your lathe have 4 thou back lash it wont dee it:wall::wall::wall: you would be 100 time better with these
http://www.busybeetools.com/products/digital-remote-readout-0-6in-in-and-metric.html they do measure your movement and not the count of pulse. Some people don't like them:hDe: I do this is what I'm using on my Taig lathe
where are you in Canada ???

beside you will save half the price Rof}Rof}Rof}

The point about back lash in (most) rotary encoders is true, but I understand that this is acceptable due to the nature of manual lathe work. I.e. You always take up the back lash in approaching the cut.

That said, the iGaging linear scales from Busybee and others aren't particularly accurate. I doubt 100 times would be the improvement in accuracy.

There are some interesting websites looking at improving accuracy: Yuritoys is worth a look. I've found a source for reasonably accurate magnetic scale tape (at a decent price). A high resolution I.e. 12 bit linear encoder module can be had for less than $20 per head, plus mounting. Making up a decent quadrature encoded magnetic scale shouldn't be too difficult.

Take a look here for the android DRO project. http://www.yuriystoys.com

Doug

 

[canadianhorsepower]

That said, the iGaging linear scales from Busybee and others aren't particularly accurate. I doubt 100 times would be the improvement in accuracy.

Doug

Sorry Doug but I don't agree. I have that type of scale on my Taig lathe and love them. THE problem is because they are cheap people
usually make bad instalation. They simply don't take time to measure that the max deflextion is .001 the total lengh. The fact that the scale are narower
then a Sino, Acutrack and other well known DRO makes it worst. anything longer then 6inch need a support in the middle to make sure
that it does not flex
I would sugest them anytime

 

[Nitrous]

Sorry Doug but I don't agree. I have that type of scale on my Taig lathe and love them. THE problem is because they are cheap people
usually make bad instalation. They simply don't take time to measure that the max deflextion is .001 the total lengh. The fact that the scale are narower
then a Sino, Acutrack and other well known DRO makes it worst. anything longer then 6inch need a support in the middle to make sure
that it does not flex
I would sugest them anytime

I believe you're talking about sine error which is a fact regardless of what linear scale you use. But the quoted specs for iGaging are not great, especially in the context of a lathe.

Description (from the iGaging site)
Accuracy: ±0.002” per 6inch Repeatability: 0.001”
Battery: 3V CR2032 / Environmental Friendly
Reading: 0.001” / 0.01mm / inch fractional

If +/- 2 thou with a repeatability of 1 thou is good enough, no problem but I don't believe that the statement "100 times better" is anywhere near close to true. The usability of the rotary encoder on a lathe presupposes that the gross backlash in the screws are taken care of by the nature of dialing into the cut, rather than the idea that most machinists dial in AND out of a cut.

Admittedly, there is a "better" grade of iGaging (previously it was "AccuRemote Digital" but that has been discontinued and replaced with a much more expensive iGaging Absolute) but the price is double or more what the DigMAG versions are priced at.

iGaging ABSOLUTE specs

• 0.0254mm/0.001in over a 150mm/6in range
• 0.0381mm/0.0015in over a 300mm/12in range
• 0.0508mm/0.002in over a 610mm/24in range

That's twice the accuracy of the regular iGaging products


Anyway, if you're happy with it, that's all that counts, right?

Doug

 

[canadianhorsepower]

Accuracy[/B]: ±0.002” per 6inch Repeatability: 0.001”
Anyway, if you're happy with it, that's all that counts, right?

Doug

Hi Doug
Accuracy: ±0.002” per 6inch Repeatability: 0.001”

I think it is acceptable cause it's over inch and being on my taig
there is nothing bigger then 3inch on it.

even on my Seig or my 13x36 my mill that have Mitutoyo I don't
trust them for the finish I will reset everything with what my micrometer would read

cheers

Luc

 

[Nitrous]

I have a compact 5 and a Craftex 7x that I'm looking at putting magnetic scales on.
I have the DigMAG by iGaging, but I am interested in finding a cheap, Magnetic Scale source.

I used to think that rotary encoders have no value in Lathe work but I did a little research looking into it.
There are rotary encoders that strictly go onto the screw. Certainly accuracy there needs addressing at the operator level. But 2 thou over six inches doesn't mean 1/6 x 2 thou over 1" when dealing with smaller parts Accuracy, Resolution and Precision all come into play here.

There is a Canadian solution that actually is a combination of a linear encoder coupled with a rack and pinion assembly. They basically eliminate backlash at the pinion gear level. Not sure if it's simply due to preloading the gear to the rack or if they actually use something like a split pinion gear.

My luck changed when I sourced (~$30/metre) Bogen-Electronics 1mm pitch magnetic scale material. Close to glass in terms of accuracy but with costs many times lower.

Doug