On Friday 22 April 2016 11:59:09 Dave Cole wrote: > On 4/21/2016 10:05 PM, Gene Heskett wrote: > > On Thursday 21 April 2016 18:59:36 andy pugh wrote: > >> On 21 April 2016 at 23:45, Gene Heskett <ghesk...@wdtv.com> wrote: > >>> Are there such beasts available, perhaps in a .750" or 20mm bore? > >>> What I've found didn't have the stroke. > >> > >> Bicycle pump? :-) > > > > I haven't seen one of those in 50 years on this side of the pond. :( > > I assume you are refering to the pumps that used to live in clips on > > one of the connector pipes from the crank hub to the steering head? > > > > Cheers, Gene Heskett > > I think that Harbor Freight may still sell them. The frame mounted > pumps are still available.
I'll tyake a look, thanks. > Ebay is a great source for Bimba type cylinders as well. Some of > them have very low drag pistons. > They would make great balance cylinders if you have a big enough > pipe/hose connecting the cylinder to the reservoir. I have explored that mentally, and came to the conclusion that the air moveing back and forth would need to be passed thru a pressurized reservoir so that it had to bubble thru the oil at least when it was returning to the cylinder in order to carry an occasional drop of oil mist to the cylinder. But I am not convinced that could be achieved without some reed valve contraptions to do the steering. It certainly would seem to be something to investigate, particularly after the first cyclinder failed from an adequate level of lubrication. The gas springs would seem to be usable, until the restrictions on the rapids are concerned. That, and in a constant motion situation as opposed to just getting the grocery's out of the car a couple times week would certainly expose the failure mechanisms, which in my experience is a gradual loss of pressure I surmise is deteriorated sealing ballons in those things. > Don't overlook the regular air cylinders also, particularly the oil > free ones that SMC and Festo sell. Two more search terms to add to the google/fleabay searches, thanks. One of the things that is pushing me toward the springs is that they are under tension and will essentially maintain a straight line between the upper idler pulley's & back down to the anchor points. The pressure cylinders OTOH are always pushing, subjected by bumping to micro bends that would destroy them over the longer haul just as its a failure mechanism in those used as lid lifters in the auto industry. The variability of the springs should not be a huge problem if they are operating in the stretch length range that assures they are still well stretched at their minimum length in service. As long as the maxumum length in service does not exceed the maximum length the spring can be pulled out to without a permanent stetching. I have been pleasantly surprised by how far the common screen door spring can be stretched. I have exceeded 4 feet without apparent damage. So I would have I think a decent amount of support starting from an anchor on the back wall of the base cabinet, up over a couple of pulleys on brackets on the top of the motor and back down to a spot on the lower end of the carriage slider. One on each side in this case. With the $5 pulleys flanges only being 3/8" wide at the outer edges of the flanges, if I have to move to bigger springs, it would make sense to make some catcher pieces to prevent a spring from rolling off that narrow a flange. The thought also crossed my mind to see if I could chuck the pulley somehow, and with a ball bearing in the toolpost, roll that flange wider to reduce that potential for a whap in the face. :) But first I have to see if I can get this 7x12 back into serviceable condition since the chatter that broke the carbide chips also unscrewed the home made housing over the motor, which itself contains all the motor driver stuffs. I think I will be forced to drill & tap more holes in the back edge of the bed under the headstock, 2 weren't enough. BTW, craigslist bombed on a lathe search, $2000 for a South Bend 14x30 that had to be at least 80 years old, huge motor on a carraige 2 feet above the spindle shaft, and an almost skeletal looking headstock and bed. Probably babbit spindle bearings to boot. Nope. Theres a 100+ yo Porter right here in town, 16x72 or such, sitting out in the weather for at least 3 years that I know of. Babbit bearings with a need for about 1/8 inch in shim washers to take up the end play. Motor apparently failed and thrown away (or sold) at some point in the dustbin of history. $500. He says the scrap iron is worth that but if so, why hasn't he recycled it? But while it all still moves, just the screws to ball screw it would probably be north of $1500. And its as much too big for me as this 7x12 is too small. > Dave Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Find and fix application performance issues faster with Applications Manager Applications Manager provides deep performance insights into multiple tiers of your business applications. It resolves application problems quickly and reduces your MTTR. Get your free trial! https://ad.doubleclick.net/ddm/clk/302982198;130105516;z _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
