Search found 163 matches

by mrfoo
Mon May 25, 2020 5:51 am
Forum: Combustion Cannons
Topic: I was hoping for some feedback on my oxy-propane combustion cannon.
Replies: 3
Views: 91

Re: I was hoping for some feedback on my oxy-propane combustion cannon.

Personally, I wouldn't use PVC for anything involving compressible fluids at pressure, certainly not for combustion chambers, and doubly not so for anything involving oxy-gas mixtures. But that's just me, I like to keep the parts of my body complete and attached where they are. For air and propane, ...
by mrfoo
Mon Apr 27, 2020 1:18 am
Forum: BB, Airsoft, and Pellet Guns
Topic: Help with making a diy blowback system
Replies: 7
Views: 445

Re: Help with making a diy blowback system

Boyle's Law tells us that, for a constant temperature, pressure is inversely related to volume, so for a fixed quantity of gas, if we reduce the volume by a factor of 2, we raise the pressure by a factor of 2. So, if we assume you have a 100mL chamber at atmospheric pressure, and you want to raise i...
by mrfoo
Tue Apr 14, 2020 1:00 am
Forum: Off-Topic Hobbies
Topic: "Offtopic-posts-topic" NSFW
Replies: 6619
Views: 241873

Re: "Offtopic-posts-topic" NSFW

Machine tools might possibly be valid reasons for divorce.

Selling my machine tools after a divorce would be a valid reason for "disappearance"
by mrfoo
Sun Apr 12, 2020 2:59 am
Forum: Off-Topic Hobbies
Topic: "Offtopic-posts-topic" NSFW
Replies: 6619
Views: 241873

Re: Re:

CX500 That's the "custom" maggot, right? Do like those reverse comstars. The standard CX500 was the ubiquitous super-cheap courier bike in London in the late 80's / early '90s. Known as the "plastic maggot", and usually brush-painted matt black (mine certainly was), they were loved and hated in equ...
by mrfoo
Tue Mar 17, 2020 1:41 am
Forum: Off-Topic Hobbies
Topic: Waste oil burner
Replies: 17
Views: 3104

Re: Waste oil burner

Tim Taylor the character in "Home Improvement", or Tim Taylor the producer of the UK's archaeology programme "Time Team"?

Either would work.
by mrfoo
Mon Mar 16, 2020 2:32 am
Forum: General How-To & Discussion
Topic: Short question topic
Replies: 1463
Views: 84776

Re: Short question topic

Porting and piston form is going to be important to get air out of a short, squat, cylinder into a long, slender, barrel in a hurry. The big issue is, IMO, going to be changing the direction of the air, as such I'd probably go for a conical piston face mating to a conical cylinder end, with highly r...
by mrfoo
Fri Mar 13, 2020 4:02 pm
Forum: General How-To & Discussion
Topic: JSR's workshop chronicles
Replies: 26
Views: 3409

Re: JSR's workshop chronicles

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, whi...
by mrfoo
Fri Mar 13, 2020 11:00 am
Forum: General How-To & Discussion
Topic: JSR's workshop chronicles
Replies: 26
Views: 3409

Re: JSR's workshop chronicles

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 ...
by mrfoo
Fri Mar 13, 2020 4:38 am
Forum: General How-To & Discussion
Topic: JSR's workshop chronicles
Replies: 26
Views: 3409

Re: JSR's workshop chronicles

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/32844760798.html?spm=a2g0o.productlist.0.0.1f77e078Ulzxga&algo_pvid=424a8b8d-51a6-4e9c-9d58-ccce3a53415d&algo_expid=4...
by mrfoo
Fri Mar 13, 2020 1:54 am
Forum: General How-To & Discussion
Topic: JSR's workshop chronicles
Replies: 26
Views: 3409

Re: JSR's workshop chronicles

I'd suggest here : https://shahe.aliexpress.com/store/group/Digital-Linear-Scale-with-Remote-Display/927893_510310119.html?spm=a2g0o.store_home.pcShopHead_6129028.1_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, i...
by mrfoo
Thu Mar 12, 2020 1:32 am
Forum: General How-To & Discussion
Topic: JSR's workshop chronicles
Replies: 26
Views: 3409

Re: JSR's workshop chronicles

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...
by mrfoo
Wed Mar 11, 2020 12:13 pm
Forum: General How-To & Discussion
Topic: JSR's workshop chronicles
Replies: 26
Views: 3409

Re: JSR's workshop chronicles

Oh, my. That's shit design. Really shit design. What I'd probably do, if possible, would be to find a way to position and then block #25 exactly where it should be, /temporarily/, then drill and ream for a couple of locating pins to hold everything square. You can then enlarge the bolt holes if nece...
by mrfoo
Tue Mar 10, 2020 12:23 pm
Forum: General How-To & Discussion
Topic: JSR's workshop chronicles
Replies: 26
Views: 3409

Re: JSR's workshop chronicles

For the cross slide, you'll need to blue up the surfaces and find out where it's interfering. Unless there's a serious geometry issue it's probably a couple of high spots. I'd start by stoning the surfaces with something very very fine, you should be able to see high spots as "polished" spots, then ...
by mrfoo
Tue Mar 10, 2020 12:20 pm
Forum: General How-To & Discussion
Topic: JSR's workshop chronicles
Replies: 26
Views: 3409

Re: JSR's workshop chronicles

Normally if you're doing longitudinal turning, you'd be using automatic feed set to the correct speed WRT the depth of cut. Usually there's a way of setting a stop that disengages the feed. Using the correct feed rate and the auto-feed will improve your surface finish, too. On my lathe, of course, y...