(03-13-2012 8:32 PM)Fly So Hi Wrote: (03-13-2012 7:21 PM)gentlmentlemen Wrote: We would need accuracy relative to the distance which the single volume pipette must travel, and as such the first and most important thing in my mind is to look at how far the button/plunger on the back of pipettes travels for various pipettes, or whether it's all the same.
For fixed volume pipettes, i think the distance is the same. For variable volume ones, the distance changes. Anyway, we could work with a large pipette, like 1000uL. As i see it, the amount of liquid drawn will be based on the number of turns the linear actuator will do to pull up the plunger, not on the volume of the pipette itself, am i right?
Just to be clear then, the fixed volume ones don't change button depression distance from brand to brand then?
And I was also thinking a 1000uL one. Anything else would have potential to take waaayyyy too long with the fixatives and carriers. Or at least I expect it would with how much we'll be slowing down the linear actuator's motor to achieve the accuracy we want. But time issues outstanding, there's also the issue of increased inaccuracy from having to repeatedly draw liquid and expell it from the same bottle.
(03-13-2012 8:32 PM)Fly So Hi Wrote: (03-13-2012 7:21 PM)gentlmentlemen Wrote: ...we'd have a grid from somewhere around 270 to 450 square inches for the whole grid, but I'm shooting pretty large there.
How many concentrate bottles are you thinking of?
A lot. Total bottles I'm thinking 30 to 50. The main reason I think it should have a lot is because if you look at the DIY stuff and the huge number of molecules being uncovered by Chris and dbot (big list at HtH), we'd need actually quite a bit more than that I think. Even without that insane amount of additions I could probably justify 30 to 40, theres just so freakin many... and thats not even counting the various cover fragrances for adding, and at least 2 carriers.
Which reminds me: it should remember which bottle type you used for later. There's a lot of stuff like that it should remember though... gah. I've got to remember to leave that user interface for last.
Either way, I'm thinking 30 to 50. It sounds crazy, but if its going to become the main way I make mixes, having less than that many might require semi frequent to frequent changing of bottles. Maybe that isn't so bad though...
For the first design (that uses the grid anyways), I'm thinking like 2 rows of 5. First row for testing if it can make it down the track, 2nd row for testing if it can make it around the bend in the track.
(03-13-2012 8:32 PM)Fly So Hi Wrote: They'll be needed for sure.
We'll see. I hope not but I expect you're right.
(03-13-2012 8:32 PM)Fly So Hi Wrote: (03-13-2012 7:21 PM)gentlmentlemen Wrote: But I think that as soon as you touch it to another material (including the surface of the liquid in the mix bottle) then the same strong cohesive and adhesive forces keeping it stuck to the tip of the pipette would be combined with gravity
Good point. So the tip must dive into the final bottle. The way i can think of now is if we use a tip rack and after each liquid is dispensed, the tip is replaced.
Well, if the machine can accurately enough keep track of the height of the liquid in the final bottle, then it ought to be able to just touch the drop to the surface, but we've already accumulated more than enough reasons I think for replacing the tips, so I say plunge it in.
(03-13-2012 8:32 PM)Fly So Hi Wrote: (03-13-2012 7:21 PM)gentlmentlemen Wrote: The only significant problem I see right now would be dealing with the variance of drop size, but I would think that would primarily be determined by the carrier, and in addition I'm willing to bet that it will either be fine, or it will be a really large drop compared to the accuracy of the machine.
Remember pipettes work with volumes, not drops. 200uL of crude oil is, to a pipette, the same as 200uL of alcohol. Besides, fixative is not something you need microscopic precision for. And if we implement the item above, this issue is history.
I was talking about the size of the drop which hangs off the pipette at the end with the thicker liquids, which depends on surface tension.
But agreed, lets just implement the method of plunging the tip in slightly and be done with it. If we're replacing the tips anyways, it should pretty much be a non-issue. The only thing I can think of would be residue on the sides of the tip of the pipette adding to the amount put into the final mix bottle, but if they don't worry about that with the .2uL accuracy ones, then I figure it probably isn't really an issue. If it is, then we'll just minimize the amount that goes below the surface --mainly on the expulsion that is. The stuff on the outside of the tip
may be an issue, but the air bubbles from not keeping the tip submerged in the concentration bottle are a
known issue.
(03-13-2012 8:32 PM)Fly So Hi Wrote: Oh that's cool. I just illustrated it because i wasn't sure that's what you meant. Anyway, i drew only one bottle but my idea was that the dark grey part is just one big part serving all bottles.
Roughly like this:
![[Image: 2174332_big.jpg]](http://www.govgroup.com/images_products/2174332_big.jpg)
This way we just use a single mechanism to uncover all of the bottles, be it a magnet or whatever.
Looks good, although I have to say I'm pretty sold on the single bottle cover idea now. I just see the changing of lid covers when you change what bottle is in what slot and switch one out being a lot easier if each bottle has its own. Could allow for a more custum seal on each bottle too which would probably work better. Gets around any potential drip issues from condensed liquid getting on the cover, or if the liquids get sloshed onto the top from the thing being bumped...
If we did single bottle covers, I would probably use the motor for raising and lowering the pipette tips into the bottles for opening the covers of the individual bottles instead of the track motor.
Also, this way only the bottle being worked with at any given time is open. Not only does that mean that the other bottles won't be open with their contents evaporating into the air during the mix making process, but it also means great things for if the whole rig gets bumped.
With the "one lid to rule them all" lid, if the machine gets bumped while mixing,
every single bottle would get sloshed. Thus, one little accident could lead to a lot of wasteage of product and money, as well as contamination of a lot of the bottles.
If each bottle gets its own lid though and it gets bumped, then whatever bottle is open at the time will still get sloshed and there will still be some wasteage of product, but it will be far less and in addition there will be no risk of it getting into the other bottles.
The main reason I thought we should just have one lid at first was because I knew I didn't want to deal with the screw caps of each bottle, but I think we could come up with a cap that stayed with the bottle-holder and was attached to it wi either a sliding track or a hinge.
The lowering of the pipette tip towards the bottle could open the cap, and the raising could close it. I'm thinking a hinge would be easier and cheaper for a single bottle cap design though. What type of securing of the cap do you think would work best? I'm thinking some type of latch one, like a snap close cap. The motor ought to still be able to operate that if the cap extends past the hinge or past the latch to give the motor lowering the pipette some leverage. Then it would just be a matter of a little stationary arm which preceeds and pipette tip to open/close the cap. At first I was thinking of maybe using some rubber bands to have the cap be self-closing, but then I thought that might be less reliable.
That reminds me of another problem which has been bouncing around in my head for the multi-cap lid solution. If it is all one lid, I would expect that a decent amount of force would need to be applied to make sure it is sealing all the bottles. If that force is not applied evenly, it may take a lot of force to seal the bottles which don't recieve much of that force. Of course I suppose you could just add some lead weights above each bottle. That would be simple enough.
Still, I think it would also have a tendency to have worse seals unless we used only one bottle type, simply because it would be difficult to adjust the middle bottles' height correctly (which would be harder to view once more bottles are in there).
But the main reason is because that looming accident scares me. Having the entire phero collection all open at once is just asking for disaster to strike with her cruel hand imo.
The one other thing I forgot to mention is that in my seal's design I had pictured an uncut square of the sealing material being pressed down on the bottle's top. I think yours would work better (with the hole in the middle) for bottles of a specific top size and shape, but when dealing with a multitude of bottles I don't know how that would work.