Cutting an ally block

[Wendelspanswick]

I think it's the fact that the smallest unit is 1 cm which is quite large in the scheme of things, if something is 10.3cm it makes more sense to use 103mm and save the decimal point.
When I drew up the plans for our house and our barn I still used mm.

 

[Parm]

Oh no - I'm still clueless when watching American youtube videos when people talk about "going from 3/8th of an inch to 1/4, taking off 17 thousandths at a time". Why would you not want to work in a unit that is divisible by ten?

Just way too complicated for me, even more so when using a micrometer to get to a couple of thou'

 

[Wendelspanswick]

To be fair the important thing is to make sure that you specify what units you are using...

 

[mike os]

Just a small point, I was taught that only cloth comes in cm, or furniture from Argos!

As used by cdt teachers everywhere. ....

 

[piman]

Hello Scotti,

why do you ask, going from 3/8" to 1/4 is taking off 125 thou or 0.125" (Why he's talking about taking 17 thou at atime I don't know, when I was doing my Time I was taught to hog off as much as possible, within machine limits). If you have an imperial machime, it's easier to work in inches.

Alec

 

[JEZGUZ]

I think the 17 thou was just a random figure to illustrate the units of measurement rather than an actual quotation.

 

[skotl]

Hello Scotti,

why do you ask, going from 3/8" to 1/4 is taking off 125 thou or 0.125" (Why he's talking about taking 17 thou at atime I don't know, when I was doing my Time I was taught to hog off as much as possible, within machine limits). If you have an imperial machime, it's easier to work in inches.

Alec

I think the 17 thou was just a random figure to illustrate the units of measurement rather than an actual quotation.

Indeed! No matter how may thous they were, I wouldn't know what it was

 

[skotl]

Back on topic , this is what I started with;

I had an old blade in the Rage so thought I'd start with that, but it was useless.
Replaced it with the new blade that I bought a few weeks ago and it went through it like a knife through butter. Used plenty WD40 and it created tons of little angry aluminium swarf;

Then over to the lathe to start rounding the first end. Learned how to swap lathe chucks, and also even up the bar in the 4-jaw

Aluminium really retains heat!

 

[skotl]

Took an hour to get it turned down to 25mm (the block started at 35mm across).

Not sure whether I wasn't being brave enough in terms of how much to take off at each pass (~1mm), and how fast to travel (slowly!).

 

[addjunkie]

Have to agree on the wood cutting band saw, ive cut up chunks the size of breeze blocks, saves loads of milling time too.

Show us a picture of the cutting tool tip, with ali you should be getting a better finish.

 

[ronan]

Aluminium really retains heat!

Nope, it doesn't, thats why its used in cylinder heads and things like that, it dissipates heat so well. But you are doing an interesting project, keep the photos coming .

 

[skotl]

Have to agree on the wood cutting band saw, ive cut up chunks the size of breeze blocks, saves loads of milling time too.

Show us a picture of the cutting tool tip, with ali you should be getting a better finish.

Just going to pop back to the garage - I might try a different cutter to do a quick skim before I take that end out of the 4-jaw.

 

[Wedg1e]

I have a vertical wood bandsaw and would probably free-hand a length off that slab. Otherwise I'd use the Bridgey in horizontal mode and slice it with a narrow 4 or 5" slitting saw.
I'd also always aim to have as little metal hanging off the chuck as possible; I know the tailstock centre is in but you only need a midgie's todger of setover and your part still ends up tapered due to the reducing diameter, it's exaggerated by the longer workpiece.
I'd also shorten the tool overhang and maybe have a bit of stiffness in the cross-slide gib strip, both of which could help with the finish.
Good effort on setting up a 4-jaw, takes infinite patience sometimes

 

[addjunkie]

Good effort on setting up a 4-jaw, takes infinite patience sometimes

Usually takes somewhere between 30 seconds and 3 hours....


What sort of speed you running at?

 

[skotl]

I have a vertical wood bandsaw and would probably free-hand a length off that slab. Otherwise I'd use the Bridgey in horizontal mode and slice it with a narrow 4 or 5" slitting saw.
I'd also always aim to have as little metal hanging off the chuck as possible; I know the tailstock centre is in but you only need a midgie's todger of setover and your part still ends up tapered due to the reducing diameter, it's exaggerated by the longer workpiece.
I'd also shorten the tool overhang and maybe have a bit of stiffness in the cross-slide gib strip, both of which could help with the finish.
Good effort on setting up a 4-jaw, takes infinite patience sometimes

Cheers!

Looks like the tool I used this afternoon wasn't sharp enough (or possibly fitted poorly) - I tried another cutter tonight and it came out much better.

That's the square section faced off (is that the right term?) on the mill, too

Next stage is to make up a fancy quick release system to mount it on the handlebar post.

 

[DAPPH]

Oh no - I'm still clueless when watching American youtube videos when people talk about "going from 3/8th of an inch to 1/4, taking off 17 thousandths at a time". Why would you not want to work in a unit that is divisible by ten?

Humour and history , raise their mirthful head here : -

Where is the skill in working all the way through a job to the base of ten when even a monkey can do it ? Mental agility at numbers and measurements brings forth an amazingly alive brain .. 10 , 10 , 10 , 10 & multiples of it does not .

All this 7/8 3/16 & 7 /64 ths etc. comes from cutting timber to size once it's been naturally seasoned ( 1 year of seasoning per inch of log thickness usually ) and then taking off the allowance for planing it to a set size that became common to skilled tradesmen .
Once we learnt how to make a saw mill and cut a log efficiently into baulks and planks the fractional imperial measurements followed as day follows night as the log lost the 1/4 or 3/16 ( The thickness of the saw blades width ) as saw dust . So inch planed stock wood is 1 " thick wood cut on the saw bench then planed to 7/8 inch .

We now see the legacy of changing to metric and it looks awful .... pre 1966 brick work was imperial sized . The metric does not match exactly so any bare brick pre 1966 ( ish ) that has metric extensions in bare brick are out of kilter in the run of the courses . Having the thinner 10 mm mortar joints on metric brickwork against the old 1/2 " ones only servers to highlight the disparity .

The other imperial fractional measurements became the norm thanks to a certain Mr Whitworth who made a machine to make very accurate reproductions if his preciselydesigned & tested nuts & bolts from the quality of steels available at that time in our history , along with people like Stephenson , Babbage Brunel etc etc etc .

The whole world worked with & was using imperial with great success , it was only that bandy legged numskull called " Bonaparte " that queered the pitch.
For Ole Boney hated the Brits so much that he legislated that La France would have it's own measurements , that any French man or woman could understand . A most had Frenchies at least ten toes or 8 fingers & two thumbs , so they were able to count up to 20 using their noses . Meanwhile the clever Brits & the other parts of the world had plenty of brain power to work in any numerical base .

The slovenliness of the metric system spread across Europe like a dose of French Palace syphilis , due to other countries being adjoined to France . Which is not surprising as it is after all a French malady
Did you know that Germany was making imperial sized machinery right up till about 1955 .. I used to repair BUDE static & spark free diesel engine driven machinery that was made in 1935 & earlier & was still used in a former WW2 ammo depot in Germany in 1972. Everything on them was Whitworth threads & cut to exact imperial sizes .

 

[skotl]

Usually takes somewhere between 30 seconds and 3 hours....


What sort of speed you running at?

Literally tried every speed the lathe could do, and ended up running at its fastest (which is either 600RPM or 900RPM - I forget...).

 

[roofman]

Hey Scott,looking at your cut finnish it looks to me you need more chuck speed

 

[addjunkie]

Are you using the slowest power feed, or turning the wheels by hand? Id also suspect the rake angle to be wrong too.

Do you have any basics books to guide you a bit!

 

[skotl]

Hey Scott,looking at your cut finnish it looks to me you need more chuck speed

Doesn't have any more chuck speed!

Are you using the slowest power feed, or turning the wheels by hand? Id also suspect the rake angle to be wrong too.

Do you have any basics books to guide you a bit!

Turning by hand (no power feed). You're almost certainly correct about the rake angle - I have the lathe book that everyone recommends (the old one - forget it's name!), but having it and reading it are two different things!