What About The Bee

Hello Mr. Peev I was playing with SCARM and there is something bothering me. I am using the default for Settings->Edit-> Tolerance->Distance = 2vmm. I placed a straight section of Hornby R600 at start point X=0, Y=0, A=0. R600 is 168 mm long. Then using the start point tool again, I selected 165,166, 167, 168, 169 and 170 mm, each in turn. See attached image The tolerance is not uniform around the perfect 168 mm. SCARM shows no join at 165 and at 170. If 170 fails, so should 166mm. Alternatively, if 166 joins, then so should 170. Both are precisely equidistant from 168 mm. Part Two I attempted to set my own tolerance, but was very, very surprised that SCARM would not let me set anything below 1mm. If I am setting the tolerance I want, why is SCARM trying to stop me?? I understand that you should not permit negative numbers, but zero and above should be valid. If I want to check for a perfect nominal join, why should I not be permitted to do so? I get the result I ask for and will suffer the consequences. If my tolerance is 1 micron, and nothing is shown as joined, whose problem is that? Mine! Thank you kindly for reading this and possibly considering it. [Bee] ÷÷÷ I will update should I hear from him.

Most small can motors have a + near the terminals. That would be (typically) red. Bee

Attaboy @Dodge1965! Well done! Bee

Well, that was somewhat disappointing. The minimum value you can set for Tolerances->Distance is 1 mm. You can set floating point values, like 1.5 mm, but anything below 1 mm reverts to 1 mm. I tried the special case of 0.0 mm, to demand mathematical perfection of each join. Sadly, this was also reverted to 1 mm. Bee

@Peachy Just self report yout erroneous event to the tireless moderators. sorted! Bee

A new fangled computer? I prefer my news over the telegraph, by Morse Code. -.-. .- -. .----. - / .-- .- .. - / ..-. --- .-. / .- / - .-. .- -. ... .-.. .- - .. --- -. / ... - --- .--. / .. / .-- --- -. -.. . .-. / .-- .... --- / .-- .. .-.. .-.. / -... . / ..-. .. .-. ... - / ... - --- .--. / -.-. .- -. / -.-- --- ..- / -.-. .-. .- -.-. -.- / - .... . / -.-. --- -.. . / ... - --- .--. / -... . . / ... - --- .--. Properly typed out, on a typewriter, of course @ntpntpntp Bee

Thank you yes. I have been fiddling around with the system. I can see a calendar at https://community.hornbyhobbies.com/events but hilariously, no way to get there from here https://community.hornbyhobbies.com I am using mobile, not PC. It should be a selection from that page, but I simply cannot find it (under the assumption it is there) Bee

Where would I see Peachy's, or indeed anyone else's, event? I understand how to make one. Under strict moderator warning, I will not make one for my "Its Friday, wear a potatoe on your neck event". 🙃 Perhaps someone more bold than I will make an event so we can see how it works? Bee

Thanks for that @RB51 I note that the default tolerance in the setting box displayed is 2mm. The value I found by experiment! I will try a 1 micron setting later today, just for giggles Bee

Hi @threelink Never give up! Thomas Edison, famous inventor of the photograph and light bulb, said something in 1932, as published in Harpers Magazine. During the interview, the interviewer asked about Edison's genius. "Genius is one percent inspiration and ninety-nine percent perspiration" What I am doing is certainly not genius. I am not attempting to wear that cloak. But the ethos in Edison's statement is clear. Work hard. Never give up. Problems occur. Work harder. You can do this. Bee

@Peachy On your cellphone, it is under the + symbol at the top. Same place as add new topic or image. Bee

Thanks @96RAF I will see if I can find the tolerance setting. I was fairly astonished when it permitted +/- 2 mm without complaint. Bee

Hi Deem The H&M Duette was rated at 1 amp, so should easily handle anything on Son of Triangman's marvelous list of 1970s current draw. Do you know how old your Duette is? Bee

Recent discussions in another thread caused me to wonder, what is the tolerance that SCARM uses to suggest that your track layout joins. I decided to use R600, a 168 mm straight. I then set a new start points, near to 168 mm The first thing of note is that SCARM blesses your layout in two different ways, as a function of the overlap / gap. At the top and bottom, SCARM shows the double arrows, indicating a fairly big disconnect. At +2 mm from 168, double arrows. At -3 mm from 168, double arrows. Smaller disconnects are just indicated by double lines. You may observe them at 166, 167 and 169 mm. It is only at 168 mm that a single line appears at the gap. SCARM permits you to zoom way in, so you may inspect each join to see if its really good or just a so so join. Here is a very zoomed in image at another join, 0.059 mm apart Two lines at the join. SCARM will not show you the double arrows, since it is within 2 mm or so. But in reality, SCARM is still warning me, those tracks aren't aligned. What about 0.001 mm of error, will you see double lines? Why yes, yes you do. SCARM will tell you when you are 1 micron out, but only if you look! Bee

The enveloped gear caused a cascade of issues, but I think I found my way back out. I chose Markits Deluxe Crankpins, as the crankpin bushings thread onto the post. Unfortunately, as you can see on the right hand side, the bushing does not bottom out, there is a gap. This necessitated a complete redraw of the crank pin assembly, shown here As this pushed the piston connecting rods outboard, I was finally forced to provide a notch instead of a through hole for the cross head. The side mounted footplates became ridiculously wide and I was forced to accept that the detail shown by Issac Shaw would not be. Shaw has the crosshead going through the footplate. And then the fun began. Can I make OO Twin Sisters go around a second radius curve. The first consideration is the the mid axle is trapped by the enveloped gear. It cannot move laterally. This also means that the chassis cannot shift like OO Experiment. I check the equations for the requirements of the second axle to fit and found that indeed it will fit Since the chassis cannot move, full compliance must be permitted on both sides of the chassis for the 1st and last axles. I ran the equations https://community.hornbyhobbies.com/forums/topic/36321-round-the-bend/?do=findComment&comment=394450 I found that when I injected the result (0.499 mm per side), that the chassis was too wide. I was forced to completely redraw the chassis, not only because of the lateral compliance, but that the dimensions I used for the motor did not account for any real world tolerance. I have added in some false floors in the front and rear. The boilers are now printed in parts and assembled with magnets. The electrical traces are let into the walls of the chassis, hiding them away. Its been a real struggle, but I think it resolved. Bee

Here are the equation results that resolve the lateral compliance for OO Twin Sisters. In the top of the image, I check the lateral compliance Y against the flanges of the center axle. I find that I will need 0.012 mm (12 microns) of lateral compliance. As Q, the track gap is 0.148 total, the lateral compliance Y is much less than Q. There is no issue with a fixed center axle. It will fit into the curve. The first and last axles must now have full compliance on each side. The chord formed by the first and third axles must always have the middle axle fixed, and further, the chassis does not shift. Thus, knowing the chord length Wt, I can find Y for the first and third axles, being 0.499 mm. Bottom half of equations. Note, same equations as above. With the redesign accomplished for the new parts (see OO Twin Sisters), I show here that indeed it will clearly go around a second radius curve Bee

That you wish to change the subject. You have no analysis to contradict the extensive proof provided against your original assertion. R2 is 438 mm, not 438.15 mm (17¼"), as demonstrated. It may have been this historically, but no more. Further, your diagram could also mean that the design you offered to SCARM is marginal. It can be forced to join, as SCARM will accept track as joined whenever the ends are within tolerance. But if they fall just outside that tolerance, SCARM says they don't join. SCARM does not demand that the ends are in mathematical agreement, just that the ends are "close enough". So depending upon exactly how those pieces are placed can cause your design to be joined or not. Interesting as the design may be, its a deflection with little to do with the definition of a second radius. Bee