#garfield Logs
Mar 25 2022
#garfield Calendar
03:14 AM rue_mohr: morning
04:53 AM Tom_L: morning
04:54 AM rue_mohr: having a nice relaxed breakfast
04:54 AM rue_mohr: no shoveling food to get out the door as fast as I can
04:54 AM rue_mohr: so, cant really run the bandsaw at 2:30am or I'm sure the neighbours will kill me
04:54 AM Tom_L: you won't know how to act today :)
04:55 AM rue_mohr: I want to do up the heads
04:55 AM rue_mohr: I think we need to make more springs
04:55 AM Tom_L: is it that loud?
04:55 AM Tom_L: it's in the shop right?
04:55 AM rue_mohr: oh geez that thing sounds like a banshee
04:55 AM rue_mohr: no, under the house
04:56 AM Tom_L: oh
04:56 AM rue_mohr: IIIIIIIIIIIIIIIIEEEEEEEEEEEIEIEIEEEEEEEEEEEEEEEEEEEEEEEEEEEIIIIIIIIIIIIEEEEEEEEEEEEEEEEEEEEEEEEE
04:56 AM rue_mohr: :)
04:56 AM rue_mohr: I keep a pair of earmuffs right on it, dedicated
04:56 AM Tom_L: shaun seen the parts?
04:56 AM rue_mohr: not yet, he's usually by on wed, but it was tues this week
05:04 AM Tom_L: do the holes all look the right size this time?
05:04 AM rue_mohr: yes
05:05 AM rue_mohr: I want to assemble a few
05:05 AM rue_mohr: I need more time and some more energy
05:05 AM rue_mohr: I have 5 sprayers to build that I have 4 heads 90% completed for
05:07 AM Tom_L: i never did go talk to the spring guy but it would probably cost too much anyway
05:07 AM rue_mohr: I didn't get the rest of the answers from the shop down there I asked
05:08 AM Tom_L: i can't remember who it was now
05:09 AM Tom_L: i know approximately where they are and can probably find them
05:10 AM rue_mohr: I think, to make it work, the volume would be way too high
05:10 AM Tom_L: been a long week. glad it's friday
05:11 AM rue_mohr: were capped at assembly labor now :/
05:11 AM Tom_L: probably so
05:11 AM Tom_L: do you build them one at a time or do each process then assemble them?
05:13 AM * Tom_L finished breakfast and goes to the chair to relax a bit
05:14 AM rue_mohr: I try to do batches, so I'm not switching tools
05:14 AM rue_mohr: I'm not sure how Sean is doing it
05:15 AM rue_mohr: he might do one at a time
05:15 AM rue_mohr: I batch 10 if I can
05:24 AM rue_shop4: oh he was in
05:24 AM rue_shop4: I'm not sure when tho
07:03 AM polprog: i just got a nice book on masers
09:03 AM rue_mohr: hmm
07:58 PM Tom_L: .
08:00 PM rue_mohr: ohhi I'm bnack
08:06 PM Tom_L: so what's tonight's project gonna be?
08:06 PM rue_mohr: I took a vit B complex so I'll wake up
08:06 PM rue_mohr: I'm waiting for it to kick in
08:06 PM rue_mohr: then I have a lot of heads to cut in half
08:07 PM Tom_L: how many did you end up getting cut?
08:07 PM rue_mohr: but this morning I did that sine wave shaper
08:07 PM Tom_L: sine wave?
08:07 PM rue_mohr: none this morning
08:07 PM rue_mohr: yea
08:07 PM rue_mohr: it takes a triangle wave and shapes it into kinda a sine
08:07 PM Tom_L: no i meant how many did you cnc
08:07 PM Tom_L: ahh
08:08 PM rue_mohr: One of the fellows in twitter was playing with a deisgn for one, and I wanted to trial-and-error an idea of my own
08:08 PM rue_mohr: it seems that lots of people liked it
08:08 PM rue_mohr: since the post at like 3am, a bunch of people built it
08:09 PM rue_mohr: that some fun
08:09 PM Tom_L: heh
08:09 PM Tom_L: yeah
08:09 PM rue_mohr: :)
08:09 PM Tom_L: caps?
08:09 PM rue_mohr: no resistors and diodes
08:09 PM Tom_L: huh
08:09 PM rue_mohr: makes it freqency independent
08:09 PM Tom_L: that's true
08:10 PM rue_mohr: basically the diodes act as zeners to change the angle of the triangle and you get a straight line approximation of the sine
08:10 PM rue_mohr: I was given 4 5kw power inverters at work today
08:10 PM Tom_L: kindof a bull nose instead of a ballnose cutter
08:10 PM rue_mohr: 48V
08:10 PM Tom_L: nice
08:11 PM rue_mohr: I think their 100lbs ea
08:11 PM rue_mohr: gonna pick them up on sunday
08:11 PM Tom_L: should hold the roof on
08:11 PM rue_mohr: couldn't get them in the work truck
08:11 PM rue_mohr: well, i want to see if they can filter my generator power
08:12 PM Tom_L: is it choppy?
08:12 PM rue_mohr: freqency/voltage error
08:12 PM rue_mohr: some systems will clean power for ya, most wont
08:12 PM Tom_L: what were they off of?
08:12 PM rue_mohr: some house in the bush
08:13 PM Tom_L: solar?
08:13 PM rue_mohr: just off the grid I think
08:13 PM rue_mohr: we do a lot of power systems for remote houses
08:14 PM Tom_L: crappy grid power?
08:14 PM rue_mohr: no grid
08:14 PM rue_mohr: remote, islands, mountians
08:14 PM Tom_L: ok
08:52 PM rue_mohr: am I awake now?
08:53 PM Tom_L: contemplating not being that
08:53 PM Tom_L: not much goin on here
08:58 PM rue_mohr: I'm cold
08:59 PM rue_mohr: I should go out and cut heads
08:59 PM rue_mohr: so I can bend them all up
08:59 PM rue_mohr: I'm not sure if we have more spring wire
09:00 PM rue_mohr: we were buying the spring wire from fastnell, but every time we buy some the branch we get it from closes
09:02 PM rue_mohr: and I need to finish my battery tester, the jacks I needed came in
09:04 PM Tom_L: funny, i was cold earlier and it was 60f out
09:04 PM Tom_L: killer headache but it's somewhat better
09:04 PM rue_mohr: huh, I had a headache today too
09:05 PM Tom_L: made me dizzy
09:05 PM Tom_L: what diameter wire?
09:05 PM Tom_L: regular carbon steel?
09:05 PM rue_mohr: music wire
09:05 PM rue_mohr: I dont recall the dia
09:05 PM Tom_L: i can check
09:05 PM rue_mohr: its just frustrating to have to set up a new account each time we want more
09:06 PM rue_mohr: I think I'll try grangier
09:06 PM rue_mohr: they are apparently better
09:07 PM Tom_L: .054"
09:07 PM rue_mohr: .039 rings a bell
09:08 PM Tom_L: no i just measured it
09:08 PM rue_mohr: hahah ok
09:08 PM rue_mohr: we might have one more box, I'm not sure
09:08 PM Tom_L: i can get up to .049"
09:09 PM rue_mohr: last time I was making springs I just finished the coil we had, it made like 30
09:09 PM Tom_L: oh wait..
09:09 PM Tom_L: .055" is #24 wire
09:09 PM Tom_L: 121' in a 2lb coil
09:10 PM rue_mohr: heh, well, your prompting me to get up
09:10 PM Tom_L: and i can get it i'm pretty sure
09:11 PM rue_shop4: oh we have two boxes
09:11 PM rue_shop4: 1/4lb
09:12 PM rue_shop4: by malin co
09:12 PM rue_shop4: Dia .055
09:12 PM Tom_L: this is roslau
09:12 PM Tom_L: high quality
09:12 PM rue_shop4: heh its from ohio
09:12 PM Tom_L: imported from germany
09:12 PM Tom_L: that or mapes
09:13 PM rue_shop4: ok well, two boxes, were good for a bit
09:14 PM rue_shop4: hmm I could put on sweaters and stuff and cut the heads
09:14 PM Tom_L: seems they only stock up to #22
09:15 PM Tom_L: no i can get #24 mapes $12.50 for 1lb coil
09:16 PM Tom_L: 5lb $51.00
09:17 PM Tom_L: in stock
09:17 PM Tom_L: i wonder if they drop ship to canada
09:18 PM rue_shop4: heh, were only on our.. 4th? 1/4lb roll
09:18 PM Tom_L: they're in Illinois
09:19 PM Tom_L: so it's definitely available
09:20 PM Tom_L: think big :)
09:20 PM Tom_L: that's why i got ~150 avr chips leftover...
09:21 PM rue_shop4: ok, playing with heads for a bit
09:22 PM rue_shop4: sales aren't big tho
09:22 PM rue_shop4: and were operating on one leg :/
09:23 PM Tom_L: but are they growing each year?
09:28 PM rue_shop4: I"ll check, I'll do some data,
09:28 PM rue_shop4: right now gonna cut a bunch
09:36 PM rue_shop4: interesting
09:36 PM rue_shop4: yours have a funny exit mark on the rectangular hole
09:37 PM Tom_L: on the long edge?
09:37 PM Tom_L: that's where it starts and i tried to fix that
09:37 PM Tom_L: where the cutter ramps in
09:38 PM Tom_L: i moved the start of the ramp a bit more to the middle of the rectangle to try and minimize it
09:38 PM Tom_L: some of them should look better
09:41 PM Tom_L: you can still see a little nick in the corner of the fixed ones
09:51 PM rue_shop4: ok, all 19 cut
09:52 PM rue_shop4: the mark doesn't matter, its just curious
09:52 PM Tom_L: yeah i do a cleanup pass with a .125 cutter after that too but not much of one
09:53 PM rue_shop4: 19 of yours 13 of mine
09:53 PM Tom_L: cool
09:53 PM Tom_L: that should set you up for a while
09:53 PM rue_shop4: hopefully
09:53 PM Tom_L: it would be even better if you ran out :)
09:54 PM rue_shop4: next is sanding, then bending, then hinges, then latches
09:54 PM rue_shop4: we cant keep up right now
09:54 PM Tom_L: you should toss the latches in your tumbler
09:54 PM rue_shop4: oh right
09:54 PM Tom_L: there's a slight mismatch i can't seem to get rid of
09:54 PM Tom_L: when i flip them
09:55 PM rue_shop4: oh gee, tommorow, when I can make a LOT of noise
09:55 PM Tom_L: does the slot look ok on those?
09:55 PM Tom_L: you can see how i rounded the corner
09:56 PM Tom_L: there may be a handfull of odd ones i tossed in but all should be workable
09:59 PM rue_shop4: ill see!
10:00 PM Tom_L: i noticed you taper the tabs on A9 to fit the tube
10:05 PM rue_shop4: >>started at 7<<
10:06 PM rue_shop4: yea, they get sanded down
10:06 PM rue_shop4: did I give you one bent up? no, I should have
10:06 PM Tom_L: i think so
10:06 PM rue_shop4: ?
10:06 PM Tom_L: wait.. i dunno
10:06 PM rue_shop4: I wanted you to be able to assemble one
10:06 PM Tom_L: i may have used one of mine
10:07 PM Tom_L: i don't remember now
10:08 PM Tom_L: http://tom-itx.no-ip.biz:81/~webpage/rue/Can_Holder/Can_holder_assy.jpg
10:08 PM Tom_L: no
10:09 PM Tom_L: i noticed that from the 3" pic you posted
10:09 PM Tom_L: the sanding that is
10:12 PM rue_shop4: yep
10:17 PM rue_shop4: my 13 bent
10:18 PM Tom_L: does he show on the weekends?
10:18 PM Tom_L: or just once or twice a week
10:18 PM rue_shop4: ! a tab snapped
10:18 PM Tom_L: yours?
10:19 PM rue_shop4: uh ho
10:19 PM rue_shop4: no yours...
10:19 PM rue_shop4: continueing...
10:20 PM rue_shop4: ok problem
10:20 PM Tom_L: same material as before
10:20 PM rue_shop4: the ones with the long surface grain
10:20 PM rue_shop4: breaking...
10:20 PM rue_shop4: do you think it needs annealing?
10:20 PM Tom_L: can you try heating them a bit?
10:20 PM Tom_L: yes
10:20 PM Tom_L: it's T6 material
10:21 PM Tom_L: just the tabs..
10:23 PM rue_shop4: the ones with the rust spots are ok
10:23 PM rue_shop4: but the ones that are breaking are notibly lighter
10:23 PM rue_shop4: I'm putting them aside for a sec, seeing what the counts are
10:23 PM Tom_L: k
10:24 PM Tom_L: it's the same material but a different sheet
10:24 PM Tom_L: odd
10:25 PM Tom_L: i think i have some that is right at .125 i could try next time
10:25 PM Tom_L: that stuff is a bit under that
10:26 PM rue_shop4: 10? of them seem to be that material
10:27 PM rue_shop4: I'll try annealing one
10:27 PM rue_shop4: two tabs broke on the first, one, and the next one cracked and I stopped
10:28 PM Tom_L: that sucks
10:29 PM rue_shop4: the one you circled, ... is on the ok material
10:29 PM rue_shop4: does that give you any indicators?
10:31 PM Tom_L: no
10:31 PM Tom_L: but i have some different material i'm pretty sure is ok
10:31 PM Tom_L: it's off a different rack and is .125 instead of slightly under
10:32 PM Tom_L: lemme go check
10:32 PM rue_mohr: http://ruemohr.org/~ircjunk/tempimage/p1230212.jpg
10:32 PM rue_mohr: http://ruemohr.org/~ircjunk/tempimage/p1230213.jpg
10:32 PM rue_mohr: http://ruemohr.org/~ircjunk/tempimage/p1230214.jpg
10:33 PM rue_mohr: same forming jig
10:33 PM rue_mohr: :/
10:33 PM rue_mohr: I'll try annealing one
10:36 PM Tom_L: i don't have any more of that harder stuff
10:36 PM Tom_L: so the new i'm pretty sure should be ok
10:37 PM Tom_L: it's 3" strips so i can feed them one right after the other
10:37 PM rue_shop4: k, the brittle ones all have the same grain
10:37 PM rue_shop4: lengthwise
10:38 PM Tom_L: that was the last of it
10:38 PM Tom_L: if you can somehow make them work
10:38 PM Tom_L: i thought you'd bent some of those before
10:39 PM rue_shop4: win
10:39 PM rue_shop4: proceeding slowly
10:40 PM rue_shop4: ooh crap I bent it the wrong way!
10:40 PM rue_shop4: ok, so I'v killed two...
10:40 PM rue_shop4: }:/
10:42 PM Tom_L: http://tom-itx.no-ip.biz:81/~webpage/rue/Can_Holder/A9_New/New_material.jpg
10:42 PM Tom_L: that's the new stuff
10:42 PM Tom_L: i haven't used any yet
10:43 PM rue_shop4: if you try to fold some of the offcut, does any of it just snap?
10:43 PM rue_shop4: I wonder if its tempered
10:43 PM Tom_L: what i sent you i know is tempered
10:43 PM Tom_L: either T6 or T651
10:43 PM rue_shop4: ok
10:43 PM rue_shop4: yea, the tempered is what would be breaking then
10:44 PM rue_shop4: well this slows it down :)
10:44 PM Tom_L: if you can get thru those hopefully these will be ok
10:44 PM Tom_L: sorry
10:44 PM rue_shop4: cant believe I folded one the wrong way :(
10:44 PM rue_shop4: cant fold them back, ever
10:44 PM Tom_L: no i know that
10:46 PM Tom_L: To anneal a work hardened aluminum alloy, the metal must be heated to somewhere between 570°F to 770°F for a set amount of time, ranging from just thirty minutes to a full three hours. The time and temperature are depending on two things: the size of the part that is being annealed and the composition of its alloy.
10:46 PM Tom_L: can you put them in the oven?
10:46 PM Tom_L: that's a bit warm for an oven maybe
10:46 PM rue_shop4: after being cut they generally have to stay paired
10:46 PM Tom_L: clean cycle might reach those temps
10:46 PM Tom_L: i figured that
10:46 PM Tom_L: number them?
10:47 PM Tom_L: i dunno..
10:47 PM Tom_L: the ink would burn off the toasted ones
10:47 PM Tom_L: if you did the oven, you could do them all at once
10:48 PM rue_shop4: oh I cant just serial them, ok yea
10:49 PM Tom_L: You can use an oxyacetylene torch, a propane torch, whatever's on hand that can get the material up to around 775 F. This is the ultimate DIY way of annealing aluminum.
10:49 PM Tom_L: then just do the tab end
10:50 PM Tom_L: just line them up and slowly go down the row?
10:52 PM rue_shop4: propane, its working
10:52 PM Tom_L: good
10:53 PM Tom_L: you won't need to do the whole part
11:00 PM rue_shop4: no just that back strip
11:05 PM Tom_L: you think you can save em?
11:06 PM rue_mohr: here is the one with the large hole, filled and redrilled :)
11:06 PM rue_mohr: http://ruemohr.org/~ircjunk/tempimage/p1230215.jpg
11:06 PM rue_mohr: I just lined them up and annealed them
11:06 PM rue_mohr: I'v wrecked two
11:06 PM rue_mohr: (those first two)
11:07 PM rue_mohr: I must not test the temperature with my finger tho, that will take a while to heal
11:07 PM Tom_L: i'd say
11:08 PM Tom_L: how did you fill the hole?
11:08 PM Tom_L: i won't get any more of that stuff for those parts now that we know
11:08 PM Tom_L: if i send more, i'd sure test one to be sure though
11:09 PM rue_mohr: I got some special soldering rod for aluminum when we started to fix the old heads that were broken
11:09 PM Tom_L: that new material i posted is a full .125 thick
11:09 PM Tom_L: ahh
11:09 PM Tom_L: doesn't work on cracked tabs though ehh?
11:09 PM Tom_L: :)
11:11 PM rue_mohr: well, I broke two tabs on the first one of them I hit
11:11 PM rue_mohr: the next one I cracked and stopped
11:11 PM rue_mohr: so I just annnealed it
11:11 PM rue_mohr: I'll see
11:12 PM Tom_L: i've scrapped some here too...
11:12 PM Tom_L: it still melts into other things :)
11:22 PM rue_shop4: it survived the rest of the bend
11:22 PM rue_shop4: with a bit more cracking, but its still solid
11:22 PM rue_shop4: I could fill it
11:22 PM Tom_L: good
11:22 PM rue_shop4: not sure if I should
11:23 PM Tom_L: keep it for testing?
11:24 PM rue_shop4: ok, 18 survived that
11:24 PM Tom_L: all bent?
11:24 PM rue_shop4: its funny
11:24 PM rue_shop4: yea
11:25 PM rue_shop4: we have so many design adjustments that by the time I'v saved something that needs a bit of a fix up, its terribly obsolete by the time I'd use it
11:25 PM rue_shop4: I have heads here, slightly messed up, that have 4 tabs
11:25 PM Tom_L: yeah i remember those
11:26 PM rue_shop4: omg this one doesn't even have a cnc step cut into it
11:26 PM rue_shop4: we were still doing them manually
11:26 PM Tom_L: step?
11:26 PM Tom_L: oh a 4 tab one?
11:32 PM rue_shop4: the step that holds the can
11:32 PM rue_shop4: we used to hand route it
11:32 PM rue_shop4: then we added the teeth, then we changed to have the cnc do it
11:33 PM rue_shop4: not sure when we dropped the other two tabs
11:33 PM rue_shop4: like I say, so many changes
11:33 PM Tom_L: teeth help quite a bit?
11:34 PM Tom_L: pretty soon you'll have a good part :)
11:34 PM rue_shop4: yea, the slightly dent the can to hold the rotation
11:34 PM Tom_L: then they'll change the can again
11:34 PM rue_shop4: well
11:34 PM rue_shop4: there might be interest in designing a hook that holds the can by the inside
11:34 PM rue_shop4: one of their guys suggested to try something like the plastic ones
11:35 PM rue_shop4: but I'v learned that they are a group that easily mis-represents
11:35 PM Tom_L: scribble something up so i follow
11:35 PM rue_shop4: were here cause they did not want to change from what they had
11:35 PM rue_shop4: I'll take a pic
11:37 PM rue_mohr: this is a plastic one thats known to break the first time its mounted to a can
11:37 PM rue_mohr: http://ruemohr.org/~ircjunk/tempimage/p1230216.jpg
11:37 PM rue_mohr: http://ruemohr.org/~ircjunk/tempimage/p1230217.jpg
11:38 PM rue_mohr: the idea is to maybe use some 1/8" metal to create a spring shape that snaps in a similar way
11:38 PM Tom_L: so that fits inside where the nozzle is?
11:39 PM rue_mohr: they say they have never had one break :/ cant be true
11:39 PM rue_mohr: yea
11:39 PM Tom_L: is the nozzle in the middle of the 2 fingers?
11:39 PM rue_mohr: yes
11:39 PM Tom_L: hmm
11:39 PM rue_mohr: I dunno, its a curiosity
11:39 PM Tom_L: same lever to spray it?
11:39 PM Tom_L: yeah
11:40 PM Tom_L: would require alot thicker material
11:40 PM Tom_L: more weight
11:40 PM rue_mohr: maybe 1/8" wire
11:40 PM rue_mohr: maybe springsteel
11:40 PM rue_mohr: pretty evil bend tho
11:40 PM Tom_L: i don't quite get what holds it
11:41 PM Tom_L: the top is sealed with the lip out so the inside part of the can top would be smooth
11:41 PM Tom_L: i think
11:42 PM rue_mohr: the cans have a bit of a reverse form on the inside around the sprayer
11:42 PM rue_mohr: but ya know
11:42 PM rue_mohr: hmm
11:42 PM rue_mohr: these dont work with the cans that have the larger buttons
11:42 PM rue_mohr: just a thought
11:43 PM Tom_L: yeah
11:43 PM Tom_L: doesn't look as sturdy as yours
11:45 PM rue_mohr: well
11:45 PM rue_mohr: http://ruemohr.org/~ircjunk/tempimage/p1230218.jpg
11:45 PM rue_mohr: http://ruemohr.org/~ircjunk/tempimage/p1230220.jpg
11:45 PM rue_mohr: our design has that atvantage
11:45 PM Tom_L: https://www.amazon.com/SafeWorld-International-116504-12-Original-Spray/dp/B004YEBVVU
11:46 PM rue_mohr: what funny is that the one that I made back in ~97 for my uncle, had a strap around the can itself
11:46 PM rue_mohr: i'm not sure how I set the top height tho
11:46 PM Tom_L: i thought about that too
11:46 PM Tom_L: the strap
11:47 PM rue_mohr: yea,
11:47 PM rue_mohr: an interesting thing happened
11:47 PM rue_mohr: a bit before we reverse engineered this one
11:47 PM rue_mohr: the main log sorts nephew designed a sprayer
11:48 PM Tom_L: https://www.eastwood.com/can-gun-one-spray-can-tool.html
11:48 PM rue_mohr: it was a much simpler design, pretty well done
11:48 PM rue_mohr: but it used a can strap and different trigger
11:48 PM rue_mohr: they HATED IT
11:48 PM rue_mohr: there were only a few prototypes made
11:48 PM Tom_L: that last one clips on in the same place yours holds it
11:49 PM rue_mohr: oooh thats the one ma was getting that breaks
11:49 PM Tom_L: you should make her a new purple handle one
11:49 PM Tom_L: :)
11:49 PM rue_mohr: anyhow, part of what they wanted was the design they were already using
11:49 PM rue_mohr: heh, she has an older one
11:50 PM rue_mohr: with the usage she puts on it, its not close to worn out
11:50 PM rue_mohr: one of the sprayers that came back from a sort had been used so much that the plastic handle had worn about 1/8 into a METAL trigger
11:51 PM rue_mohr: 8-|
11:51 PM Tom_L: https://rainbowtechstore.com/products/can-gun?variant=35589018638
11:51 PM Tom_L: there must be some kind of lip there...
11:51 PM rue_mohr: these things get a CRAZY amount of usage
11:51 PM rue_mohr: you notice that second link is made for a metal retainer spring thats not installed?
11:51 PM Tom_L: aparently they hold up pretty well though
11:52 PM Tom_L: no
11:53 PM rue_mohr: hah, so, if were in for hte money, we sell the whole business to someone, right?
11:53 PM rue_mohr: haha
11:53 PM rue_mohr: dont think I'd do that
11:53 PM rue_mohr: oh sales, stand by, lets project
11:53 PM Tom_L: something to occupy time
11:55 PM rue_shop4: 2017: 41
11:56 PM rue_shop4: 2018: 47
11:57 PM rue_shop4: 2019: 27
11:58 PM rue_shop4: 2020: 28
11:58 PM Tom_L: --\__
11:58 PM Tom_L: covid
11:58 PM rue_shop4: 2021: 24
11:59 PM rue_shop4: ok
11:59 PM rue_shop4: so, we should stock parts for about 30 to prep for a year