What Did You Buy Today?

[SouthernChap]

OT I know, but...

TBF, I would rather know 100% that the feet are flat/level to each other and the bedway BEFORE I spend time building the thing up.

At least then I could concentrate on getting everything else where I want it to be in terms of fitment and accuracy, as accurate as a 7x can could ever be, which is a task unto itself.

Whilst my SC3 is "doing the job for now" without any mods other than A/C spindle bearings, it does have all the "usual" problems, including the Cross slide screw nut fixings back-winding despite having thread-locked them.... Another one of those "I'll fix that B!"££$%d whilst I am rebuilding the other lathe" jobs!

Saying that, I just ordered this 1300w Brushless motor kit (£370 OUCH!) for the 7x I am rebuilding, so should be on with some rebuild work on it soon. Have almost everything I need to fully start the rebuild now, other than an ELS kit, which I am currently reconsidering whether I actually need or not, though it is an easy enough retro fit.

Yes, I can acquire spare boards for this and yes, I will be doing exactly that soon enough so that I have spares to hand.

View attachment 487909

Yep; removing the paint from the feet and the visual testing with the light and granite off cut being used as a base, and the 'rock and roll' testing were that 'starter for 10'. Once the lathe is rebuilt (I think this is my 4th rebuild) I can do some more test cuts and shim the feet where necessary.

That kit is very similar (the motor, the RPM display and the controls, although not the board, and the motor, whilst being exactly the same form factor, is 750W) to what Weiss used on my lathe.

At some point, (turns out I must subconsciously like rebuilding this lathe!) I'll swap out the 750W for a 1500W motor. Might have to replace the plastic quick change gearing set for a metal set but we'll see how the existing plastic ones hold up.

 

[GrifterGuru]

Yep; removing the paint from the feet and the visual testing with the light and granite off cut being used as a base, and the 'rock and roll' testing were that 'starter for 10'. Once the lathe is rebuilt (I think this is my 4th rebuild) I can do some more test cuts and shim the feet where necessary.

That kit is very similar (the motor, the RPM display and the controls, although not the board, and the motor, whilst being exactly the same form factor, is 750W) to what Weiss used on my lathe.

At some point, (turns out I must subconsciously like rebuilding this lathe!) I'll swap out the 750W for a 1500W motor. Might have to replace the plastic quick change gearing set for a metal set but we'll see how the existing plastic ones hold up.

TBF, I actually looked at the 1500w kit, but 1.75hp 1300w kit over the 1500w 2HP kit seemed the better option to me given the over £100 saving.
Trouble is, I will have two speed displays... Motor RPM and Spindle RPM.

 

[SouthernChap]

TBF, I actually looked at the 1500w kit, but 1.75hp 1300w kit over the 1500w 2HP kit seemed the better option to me given the over £100 saving.

Oh, the 1300W kit is over £100 less? I've not done an awful lot of research on upgrading the motor yet but yep, that sounds like a sensible decision. Useful, heads-up there; when it comes to it, I'll probably do the same.

Trouble is, I will have two speed displays... Motor RPM and Spindle RPM.

Do you have the headstock with the hi/lo backgear?

My original headstock had no backgear*. However, after an accident with a hydraulic press and some inattention on my part), I needed a new headstock and it was quicker and easier to get a headstock with the backgear present.

I just removed the backgearing, plugged the holes with some aluminium plugs that could remove if necessary, and with the motor driving the spindle directly as with my original headstock, went on my merry way (that was the 2nd rebuild if memory serves).

Ever since then though, I've been toying with the idea of installing the backgear (because the motor is positioned to drive the spindle directly via the V belt, I'd need to either extend the adjustability of the motor position or get a shorter V belt) to see if I could get even more torque at lower RPMs.

I assume the board on my lathe as it came, does some sort of calculation to provide a correct spindle RPM display (there's no tachometer or sensor for the spindle to provide a reading). Alternatively, maybe with the pulleys and V belt configuration, the motor RPM and spindle RPM are equal.

Either way, adding the backgear would probably mess up the RPM display.

So after all the above ramble, my question is whether it would be worth the effort of doing the work and the need to install a sensor and an additional display

I suppose if I actually went and measured the gearing on the backgear (currently sat in a cupboard) and did the maths, I'd be able to work out ratios and so get an idea of the gains myself but eh, if someone who knows this stuff like the back of their hand can tell me it definitely won't be worth it, I could save myself the bother of even working it out!

Of course, if I eventually replaced the motor with a 1.75 HP motor, that would probably mean that installing the backgear would have been even less worthwhile, given the limits of the lathe's fundamental rigidity.

*Weiss deleted the backgear from the design, claiming that the use of a brushless motor provides enough torque at lower RPMs not to need a hi/low gearing; same form factor though, they just didn't drill the holes for the countershaft and the lever.

 

[GrifterGuru]

@SouthernChap

TBH, I went with a geared headstcok irrespective of motor choice.

A brushless motor drops torque over 2000 RPM at least that is what most comparisons I have read show it to be.

That said... There are TWO ratios of gearing. The more common gearing is 21/29 - 12/20 spindle/layshaft gears respectively, the less common ratio, which I happen to have through sheer dumb luck, is 31/43 - 18/30 spindle / layshaft gears respectively.

A little simple math for an example...

12/21= 0.5714:1
20/29 = 0.6896:1

18/31 = 0.5806:1
30/43 = 0.6976:1

Is it worth the effort of running a geared head? I think so. High RPM is not something that is used very often and it is more often that torque is the better option.

You can see for yourself the ratio differential and decide if a) it is worth it and b) gives better torque if you use a geared head.

Re the brushless motor & tach display question.. That is why I am running a spindle speed sensor as well as the motor tach. To me it is worth it to be 100% certain of spindle speed.

The motor to spindle pulley ratio is geared DOWN so that the spindle spins a lot slower than the motor. Anything otherwise just would not work or require extreme levels of torque.

On the C3, the motor pulley is 17T, the layshaft pulley is 31T, so the ratio is 0.5483:1 which, unless I have it wrong, is just under 2:1 at the layshaft, further reduced by the gears, dependant on the ratio you use.

For the SC3 which is direct drive, the Motor pulley is 20T, the spindle pulley is 40T, so a 2:1 direct ratio.

I have actually thought of creating a hybrid ratio pair (12/21 & 30/43) for the geared headstock by using two sets of gears, machining the gears off the spacer section, then re-creating a pair with the new ratios of choice. Not exactly hard to do to be fair and would give both the lower & higher of the four total ratios between both ratio pairs.

 

[dkemppai]

TBF, I actually looked at the 1500w kit, but 1.75hp 1300w kit over the 1500w 2HP kit seemed the better option to me given the over £100 saving.
Trouble is, I will have two speed displays... Motor RPM and Spindle RPM.

What motor and controllers are you guys talking about? Do you have any links/details?

Are the speed continuously variable, or do they speed step, in say 100RPM increments?

 

[GrifterGuru]

What motor and controllers are you guys talking about? Do you have any links/details?

Are the speed continuously variable, or do they speed step, in say 100RPM increments?

CV and no links, sold out as of my purchase

 

[rwdenney]

Tired of trying to make drills work with hand-lapping, though that still works in a pinch.



And my precision ground flat stones are kind of chewed up. And they are too small. Time for a new set.



Plus some bits and pieces—a Starrett edge finder, a carbide-tipped scriber, a Starrett 6” hook rule.

Rick “sharpener was a birthday present to myself” Denney

 

[woodchucker]

Tired of trying to make drills work with hand-lapping, though that still works in a pinch.

View attachment 487950

And my precision ground flat stones are kind of chewed up. And they are too small. Time for a new set.

View attachment 487951

Plus some bits and pieces—a Starrett edge finder, a carbide-tipped scriber, a Starrett 6” hook rule.

Rick “sharpener was a birthday present to myself” Denney

Please tell me you didn't use precision flat stones for drill bits.

 

[rwdenney]

Please tell me you didn't use precision flat stones for drill bits.

Hah! No. But they eventually get chewed up through use, and I’ve used mine a LOT.

I have little EZ-lap diamond files that I use for touching up cutting edges by hand.

The old ones were also too small. But they’ll continue to serve for rough and dirty work.

Stones should only be used on surfaces that are flat, but I find myself using them to determine what surfaces are and are not flat. It’s quicker than bluing them up and checking on a surface plate for installed stuff that isn’t as critical. But it’s certainly hard on the stones.

Rick “will keep the new ones for cleaner work” Denney

 

[ChazzC]

Wear Blocks

Didn't know I "needed" these until a discussion came up on another forum (https://bbs.homeshopmachinist.net/f...ro-on-a-boring-head-yes?p=2087057#post2087057).

However, I didn't see any sense in spending more for a pair of wear blocks than I did for my SHARS set of blocks, so got these:


I contributed the wooden box. Random sizes, and an order of magnitude more precise than my gage blocks, but that's not a big deal. $35 + postage on eBay.