Member postings for SillyOldDuffer

Jason,

This link should take you to a folder containing three versions of the table for your lathe:

• wm280jason.txt (raw data)
• wm280jason.odt (open document text)
• wm280jason.pdf (pdf)

My 280 manual suggests the imperial version has a 20t and no 35t. Let me know if the gear list is wrong, it doesn't take long to add or delete them.

Dave

No problem. I'll put up a link when it's ready.

Dave

No problem, I'll put a copy in the dropbox folder when it's ready.

I'm metric, do you need imperial?

Dave

Hi Brian,

I think we all got confused with the unusual arrangement at the headstock of this lathe.

Quite a lot of lathes, including mine, have a fixed 40t gear on the headstock that has to be taken account when calculating the gear ratios. Bill's lathe has an extra stud mounted 40t gear between the headstock and the banjo. I had to play with the numbers to get my head round it.

The good news is that the extra gear doesn't alter the ratios - it's just an idler. I guess it's only there to suit the layout of the gear chain on that particular model.

Jason was referring to the built in gearbox that many of the bigger members of this lathe family have: it adds 1:2, 1:1 and 2:1 to whatever the gear-chain is producing. The WM240 doesn't seem to have it.

Only Bill can explain where the pencilled numbers for 26tpi came from. It may be a mistake, or as you suggest, it's a metric approximation.

Bill's made himself loads of extra gears for his lathe and in consequence my program churned out a raft of possibilities for 26 tpi (The list is from approx Page 263 of the 916 page pdf! )

...
66 80 60 65   1/26   0.9769     26
25 40 30 65   1/26   0.9769     26
35 65 30 40   1/26   0.9769     26
42 40 30 65   1/26   0.9769     26
90 80 60 65   1/26   0.9769     26
35 80 60 65   1/26   0.9769     26
40 80 60 65   1/26   0.9769     26
90 40 30 65   1/26   0.9769     26
55 65 30 40   1/26   0.9769     26
42 65 45 60   1/26   0.9769     26
40 60 45 65   1/26   0.9769     26
55 80 60 65   1/26   0.9769     26
90 65 60 80   1/26   0.9769     26
45 65 30 40   1/26   0.9769     26
42 65 30 40   1/26   0.9769     26
25 80 60 65   1/26   0.9769     26
55 65 45 60   1/26   0.9769     26
66 40 30 65   1/26   0.9769     26
55 60 45 65   1/26   0.9769     26
60 60 45 65   1/26   0.9769     26
60 65 45 60   1/26   0.9769     26
70 40 30 65   1/26   0.9769     26
45 80 60 65   1/26   0.9769     26
50 65 60 80   1/26   0.9769     26
50 65 45 60   1/26   0.9769     26
35 65 60 80   1/26   0.9769     26
66 60 45 65   1/26   0.9769     26
66 65 60 80   1/26   0.9769     26
75 65 60 80   1/26   0.9769     26
90 60 45 65   1/26   0.9769     26
55 65 60 80   1/26   0.9769     26
25 65 45 60   1/26   0.9769     26
80 65 45 60   1/26   0.9769     26
70 80 60 65   1/26   0.9769     26
70 65 60 80   1/26   0.9769     26
60 40 30 65   1/26   0.9769     26
...

Spoilt for choice apparently although I don't know how many of the combinations will physically fit into Bill's lathe.

I see the formula I used got mangled in the formatting of an earlier post. It is:

40   A    C   1
--  x  -  x -  x -  = ratio
A     B    D   12

edit: still mangled!

I've also noticed that in typing up my program I left out a few of Bill's gears. I'll put them in and generate an even longer list of combinations.

Nothing is ever easy is it...

Dave

Edited By SillyOldDuffer on 18/10/2016 13:06:46

Edited By SillyOldDuffer on 18/10/2016 13:08:24

Morning Nitai

I think the SAE numbers used to specify motor oil are not comparable with the similar SAE numbers used to specify Gear Oil. In practice, SAE10W and SAE70W have similar viscosities:

• SAE10W Motor Oil - 4.1 sq/mm per second at 100C
• SAE70W Gear Oil - 3.9 sq/mm per second at 100C

I think the 'W' stands for Winter and means the specification covers low temperatures, i.e the oil won't thicken unreasonably in cold weather.  (Edit: Hopper posted first, see his comment on the W)

Dave

Edited By SillyOldDuffer on 18/10/2016 12:13:02

I'm wonder if it's work hardening? You could test for that by forcing a deliberately blunted drill into a fresh part of the bar to see if you can create a hard spot. Then use a new drill in the same spot to see if it cuts.

Dave

Yes, and it would be even longer if I knew how just many 'spares' Bill has! Of course many of the possibilities are probably useless, and listing combinations like 60 60 60 60 would be a fat lot of pointless. Good job the list doesn't need to be printed on paper, or calculated manually.

I intend to simplify the list for use with my WM280 by eliminating 'odd' values and superfluous duplicates. There may also be gear combinations that won't physically fit into the banjo.

One thing has already made the exercise worth it. My manual doesn't give a combination for producing metric 0.7 threads. Luckily the program suggests combinations for 1.4 from which 0.7 is easily derived using the permanent gearbox.

Upwards and onwards,

Dave

Edited By SillyOldDuffer on 17/10/2016 20:56:59

Just in case anyone wants to see the code (Python3) here it is. Making it public guarantees it's wrong ...

import itertools # supports permutations
import fractions # for rational arithmetic

metric = [ 20, 30, 45, 50, 60, 60, 65, 70, 75, 80, 85 ]
imperial280 = [ 20, 25, 30, 40, 45, 50, 55, 60, 63, 65, 70, 75, 80, 80 ]

imperial = [ 40, 90, 75, 50, 60, 66, 70, 80, 65, 42 ]
extras = list( range( 25, 95, 5 ) )

gears = imperial + extras

headstock = 40

if gears == metric:
leadscrew = fractions.Fraction( 3, 1 ) # WM280 Metric
else:
#leadscrew = fractions.Fraction( 1, 8 ) # WM280 Imperial
leadscrew = fractions.Fraction( 1, 12 ) # WM240 Imperial

# Basic gear chain formula. NB 40 is the fixed headstock gear on some lathes
# 40 A C
# ratio = -- . - . - . Leadscrew
# A B D

possibles = []

# calculate the ratio of each permutation and add to the possibles list
for a,b,c,d in itertools.permutations( gears, 4 ):
ha = fractions.Fraction( headstock, a )
ab = fractions.Fraction( a, b )
cd = fractions.Fraction( c, d )
ratio = ha * ab * cd * leadscrew
possibles.append( (a,b,c,d,ratio) )

# Remove duplicates by converting the possibles List to a Set
possibles = set( possibles )

# Sort the set of possibles by ratio
possibles = sorted( possibles, key=lambda possibles : possibles[4] )

# Output the results
print( "{:2s} {:2s} {:2s} {:2s} {:^8s} {:^6s} {:^6s}".
format("A","B","C","D","ratio","metric", "tpi")

for a,b,c,d,r in possibles:
if gears == metric:
print( "{:2d} {:2d} {:2d} {:2d} {:^8s} {:6.4g} {:6.4g}".
format(a, b, c, d, str(r), float(r), float(r) * 25.4 ))
else:
print( "{:2d} {:2d} {:2d} {:2d} {:^8s} {:6.4f} {:6.4g}".
format(a, b, c, d, str(r), 25.4 * float(r), 1/float(r) ))

Hi Bill,

I've produced a pdf with nearly 54000 gear combinations for your delectation. I friended you in the hope of being able to send you a PM but it might be easier for you to use this link to DROPBOX.

You'll see that the table contains many different ways of generating a much smaller number of useful tpi.

It isn't a complete list: your lathe uses some set-ups like that for 12tpi that I haven't modelled.

Hope it's useful,

Dave

Thanks Bill. I've written a program to tabulate gear configurations. It works for my lathe and now I have a description I'll see if I can get it to do the same for yours.

That double 40 arrangement at top of the chain is new to me. Keep your fingers crossed.

Cheers,

Dave

Is that the exact same lathe and stand as pictured on lathes.co.uk? If so it may be unique, with you in charge of the Owners Club!

It'll be interesting to hear how you get on with it, warts and all (if any!)

Dave

Not sure if I'm answering the question but this site (search 'HV6' has a link to this table.

I'm too busy at the moment to think about how to calculate angles like 33.5 degrees but I'm sure it's possible provided there's actually an approximation close enough given a particular table and wheels.

If no-one else can provide the answer I'll have a go later.

edit: And D Hanna posted the answer while I was typing!

Dave

Edited By SillyOldDuffer on 17/10/2016 13:13:01

Hi George,

Just tried your link with Ubuntu & Firefox and with Windows 10 & edge. The site works fine with both. It does use flash, which might well be causing your problem. Could be worth reinstalling it.

Dave

Hi Russell,

I wholeheartedly agree about the relative malware immunity of Linux and OSX, it's amazing what you have to worry about security-wise on Windows!

Good point about virus checkers and how they can interfere with each other. That might have been the real reason for a previously OK AVM failing after the upgrade to W10.

Since retirement I'm ever more out-of-date about the vices and virtues of the various AVM products. I don't know anything at all about the relative effectiveness of the Microsoft built-in. Is it trustworthy do you know?

I ask because although most of my computing is happily performed using Ubuntu, I still need Windows to run various incompatible software packages and to interface with some odd hardware. I'd be delighted to simplify my Windows counter-measures if the Microsoft W10 solution was a good 'un.

Dave

Thanks Bandersnatch.

Windows 10 itself was OK on the C: drive, it was just D: and a load of data files that got whacked.

Seems the problem was due to the virus checker running amok after the upgrade, presumably not allowing access to anything on D: whilst it was away with the fairies. Daughter spotted the virus checker because it was using massive amounts of CPU.

De-installing the virus checker and replacing it with another one fixed the problem. Having feared the worst the computer owner was delighted to get her files back.

Dave

Just a progress report. I followed Neil's advice about washing up liquid etc. and heated the shank taking care not to overheat the teeth. After plunge-cooling the cutter went in the oven for an hour whilst I starved. (Gas Mark 6 is 200℃ )

Loading a aluminium blank sized in imitation of a Meccano Part 31 (a 1" diameter 38 toothed gear), I lined up the cutter for a full depth cut and started cranking. All went well until the Man from Porlock rang my doorbell and interrupted me. Now I own a unique 37½ toothed gear wheel.

Despite the miscount I'm well pleased with the gear and the cutter's effectiveness on Aluminium. I shall try brass next and see what happens...

Thanks again,

Dave

My daughter's just rung up with a tale of woe. After a friend updated to Windows 10 her D: drive reports it is completely full. Which wouldn't be so bad if all the files on it hadn't disappeared as well. C: is fine.

Thanks Brian. Watch this space - I've nothing in the bag so far and you may yet see me defeated by this one.

Dave

I'm still experimenting with ways of doing this, not just for Bill, but because I want to understand it as well.

My Chinese lathe has a fixed 40t headstock. This is bad news if you want to use an online calculator. I haven't found one yet that directly covers that eventuality.

Working back from a target tpi to find a suitable gear chain from first principles is - I think - quite difficult. Sparey says "don't calculate it - find a table". The sums are extra hard if you're not completely sure of the leadscrew!

So I'm approaching the problem the other way by calculating a table of all the pitches/tpi that can be obtained from a given set of gears with a 40t headstock, and a given leadscrew value.

Calculating such a table manually would be tedious and error-prone. As Bill has lots of extra gears, it would be extra hard in his case. Fortunately, touch wood, I have the programming skills needed to mechanise the process. It will still need careful checking though - I am the Weakest Link.

Dave

I bought a set for much the same purpose. They're not particularly good, nor are they dreadful.

The lenses are reasonable but tend to scratch. The headband soon gets uncomfortable and doesn't hold position too well. There's a bright LED mounted on the headband that usefully lights up what you're looking at.

My conclusion: worth the money for occasional non-intensive use like quick inspections. Not a good choice for regular or prolonged work.

Dave