Regarding measuring the distance between the bearings, yes, there are lots of ways to do that. However the fixture also guarantees perfect drilling of the holes at said distance. That’s why it is worth doing. It’s not just a measurement challenge, it’s a manufacturing challenge being solved. Also, rest assured everyone, as I said in the video, the entire wheel set was disassembled, cleaned, and reassembled after the heating. Your grave concerns about the Loctite on the other side are duly noted and no need to keep mentioning it, thanks!
Honestly, you probably could have removed the paint with a solvent and reapplied it if you really needed to. What's more important is the integrity of the metal which you were able to preserve.
Just doesn't seem right when its gone! Yahtzees, pickle baths, Swarfee the Duck, Sprocket conversations. Lots of responsibilities come with a successful RUclips channel.
The fact that you use your oops’s as a teaching moment is one of the major reasons I enjoy your channel so much, your combination of humility and wit is refreshing - glad to see riches and fame have not gone to your head, lol
It's been wonderful watching this project come together. Folks that are willing to not only run scale steam locomotives but actually build them are an inspiration.
The stress in CRS is primarily in the skin, so it doesn't take a very heavy cut to make it bow. Glad you found the source of the bind and got it sorted successfully. That adjustable fixture is genius. "If you can't make it perfect, make it adjustable."
Great start on your side rods, Quinn! Yes, getting those side rods to fit AND go around in circles at the same time is a real trick. You addressed the issues masterfully! Kozo's instructions and jigs are truly wonderful, I agree! But often, like in this case, the real issues are still an exercise for the reader. You solved this one very carefully and systematically. Wonderfully done, Quinn!
@@misterikkit Given Quinn's background and skills in the electronics format, she needs to do a project making a CNC laser marking system. She can put Veronica to work as the smarts.
While coming up to the arbor press my eyes kept looking for "ominous foreshadowing"... glad I can still trust you to warn us! Whew, I need a lie down after that.
I love this series of videos! My granddad Ben Nixon worked with a group of fellas to build 0-4-0 Reading camelback switchers, and kits/plans are still available today. I have a ton of good memories as a kid at PLS with both his switcher and Royal Scot.
I don’t think I’ve commented on one of your videos before, but I’ve been following this project the whole way and absolutely loving it. Thanks for everything
Genius combined with genius. Future editions of the book should be boxed with your videos. At least for actual builders- I’m quite happy to have read the book and armchair the videos.
I really enjoy your enthusiasm for Kozos clever fixtures and order of operations. And of course also enjoy seeing the cleverness of Kozo put to metal. :)
Quartering is critical. In my youth I was employed in model railroad oriented hobby shops that sold very expensive imported brass locomotive models. Mainly HO scale with a few VERY expensive models in O and S scales. There was one run of a particular locomotive where 7 out of the 10 our store had were out of quarter. When nickel silver rods a millimeter thick get bent by out of quarter drivers on an HO model, pretty is not a word you're likely to hear.
Gorgeous work as always, Quinn! Loved the jig... what a genius, Kozo. The joys of making a smaller locomotive like the A3 is, fewer side rods over all - lol! The running gear on big engines gets repetitive. My friends and I are hoping to start building a 2-4-0 soon enough, so, who knows, maybe some of your techniques might scale up. ;)
@@Blondihacksblondi. This man. This man is the man you need for stuff like this. He works at the Colorado Railroad Museum, in Golden, Colorado. He is highly experienced with trains (at least in terms of operation and mechanics), and just yes. This man is the man.
Since "clever" in programming often means "we're going to regret this later," it's refreshing that in machinery it almost always means "clever." Although in both cases, it's usually not apparent until you have to maintain it.
I think that's the biggest difference I've experienced between coding in school vs coding at a job. It seems almost always the better choice to have code that is easily understandable, even if it takes up more space. Sure, you could do the operation in one line, but if you break it up into four lines with descriptive variables and comments explaining why you are doing the operation in the first place, your future self will thank you.
Clever code is only clever until you find yourself having to figure out your own shenanigans a few months later. After that, you begin to appreciate the beauty of boring, clearly laid out code. Hopefully.
True, I have been guilty of, in the long ago past, writing code that seemed to do one thing but in effect, if you were not paying very close attention did another. Job security, I knew that if they changed that subroutine in any way the whole system would blow up. I do love case statements with custom named terms that people think are regular terms. Evil chuckle ensues.
Very interesting. You do a great job. I'm a retired Architect, but have always loved trains. I retired when I was 52 and at the ripe old age of 65, I decided to build a 4-8-4 steam locomotive. Not having any machining experience, I was VERY intimidated, but I didn't let that stop me. The scariest part of the entire build was the quartering and constrution of the side rods. Could I do it? I trusted my mathematical skills and drove on. Miraculously, I managed to get 4 drive axles and 8 wheels quartered and machined. Miraculous in my eyes, but this only testifies that with a little perseverence and determination, anyone can realize a dream. Don't be scared to try. I'm now 71 and have a running and operational 4-8-4. I know, everyone says not to start you adventure with a 4-8-4, but at my age, I didn't have time to start with a smaller wheel arrangement and I learned something. Larger wheel arrangements should not be intimidating. The techniques are exactly the same for a short wheel arrangement vs. a longer wheel arrangement. PAY ATTENTION to the details and you can get there.
When Iwant to learn something, I often try lerning on a real thing I want to do - not some practise project. It motivates you to work through problems. Likewise, if an 4-8-4 is what you really want - go for it! It'll keep you better motivated than some smaller design you only feel moderately passionate about.
I really like your videos, as a product designer and machining enthusiast, these videos inspired me to also buy a micro lathe and milling machine, and I learned a lot of useful knowledge from your sharing. When I saw that the connection shaft between the connecting rod and the wheel was a precise fit and not a ball joint, I was worried that they would hinder the swing of the front wheel's tilt suspension system. But at the end of the video, when you turned the wheel by hand, I saw that the suspension system had The swing, it seems that the clearance of the bearings and the swing range are designed just right! Good job!
This was actually extremely pedagogical - having watched this video, no one will disregard the possible issues with material stress! Seeing is believing! (I run the much smaller gauge 1 live steam size, and I actually don't want very exacting tight tolerances on axle boxes, crankpins and rods. Instead I strive for just the right amount of play, otherwise locomotives don't run smoothly.)
Great work Quinn, your process of finding the problem and the fix I think was very good. Cuttos to your patience and meticulous attention to detail. Thanks for sharing.
It makes me totally happy to know that women like you actually exist, I know its a risky statement these days, but Ill take the chance telling you.... Thanks for giving us disillusioned old guys a believe in the future. ✌️
Dumb question/suggestion, I'm sure, but: couldn't you use the side rods to accurately set the quartering on the second side? I mean, make the side rods before locktighting the wheels onto the axles, and quarter/locktight one side "fairly accurately" (as you said earlier, it doesn't really matter if 89 or 91 degrees) using a side rod (so you wouldn't need a quartering jig nor a side rod drilling jig -- just make them together as a pair so the holes are the same distance apart), and then use the second identical rod to quarter/locktight the wheels on the other side. Seems too simple, so I'm sure I'm missing something!
I do hope you removed the other wheel and crankpin, as well! The loctite on those was also compromised by the heat, and as soon as power is applied, there's a good chance it'll slip on the axle, if there's ANY slip on the wheel/rail interface of the wheel that has been freshly loctited.
The rod going banana was not a mistake, just a happy little accident. And because of this happy little accident, you showed us „normalizing“. Thank you!😉
Bro, you are awesome. (Thats a gender neutral bro, i say bro to everyone, even my wife) I have serious adhd and mild autism, your content both relaxes and educates me. Its one of the reasons I've decided to try and retrain to an engineering focused career in my 30s. Seeing your love for this craft inspires me.
Oh yea i feel u. I had to remove the retaining bolt of a 40mm udrill this week. The toolprep dude used the good green stuff and called me after he stripped the teeth of the torx head screw... It took a lot of time using the heatgun gettin all that metal hot enough to break the glue while trying not to break the extractor tool in the bolt. Burnt finger included xD
With one set of wheels properly quartered, I bet if you assembled the rear axle and wheels with the locktite wet and rolled it as it cured, it would force them to be in proper alignment.
Loving the progress, Quinn! Im curious whether you measured the hole spacing on the drilling jig, to compare against what it 'should' have been? I'd be interested to see just how close to perfect you ended up.
Well.. I guess that answers the question seen so often on t-shirts during the 1970's: "Why be normal?" (Because you don't want to become a banana, of course.)
I am curious about the tool holder you are using with the vertical tool bit , I have not seen one like that . Can you tell me more about it ? Or is there already a clip on it ?Thanks
I do a lot of Loctite. 609, 680, and 660. It won't budge until you exceed 400F. The TDS is informative, but slightly aspirational. I like their retaining compounds, but think their thread lockers are a joke. Nothing beats correct torque for a fastener. NIce work BTW. You're doing fine.
hi Quinn, a while ago you did a video showing the Shrum Solutions Tri-fly as an alternative for a flycutter. I haven't been able to find that video again, do you know which video it is?
Love this build and that is a cool fixture. Just wondering if it wouldn't be a lot easier to set the side rails up in the mill and use pin gauges and DRO to get the correct center to center distance? Great save on the wheels
Trying to figure out what happened with the mis-quartered set - if one end of the axle were elevated, that would open up the angle. Perhaps there was a chip stuck in there? I doubt it, since you work with such meticulous care, but I'm otherwise stumped. Well who cares - as you said, gettin' trainey!
I’ve wondered as well, because the quartering was too wide, which makes no sense. Only guess I have is that the wheels moved after removal from the fixture because the Loctite hadn’t set
Since one axle can twist and the other can't, something has to flex with the side rods, right? The pins the side rods turn on won't be parallel any time the movable axle... moves. What am I missing?
Regarding measuring the distance between the bearings, yes, there are lots of ways to do that. However the fixture also guarantees perfect drilling of the holes at said distance. That’s why it is worth doing. It’s not just a measurement challenge, it’s a manufacturing challenge being solved.
Also, rest assured everyone, as I said in the video, the entire wheel set was disassembled, cleaned, and reassembled after the heating. Your grave concerns about the Loctite on the other side are duly noted and no need to keep mentioning it, thanks!
Honestly, you probably could have removed the paint with a solvent and reapplied it if you really needed to. What's more important is the integrity of the metal which you were able to preserve.
All is good, but no Yahzeee? I feel lost. 4:07
When you don't mention the pickle tank we worry. 🤐
great repair Quenn
Just doesn't seem right when its gone! Yahtzees, pickle baths, Swarfee the Duck, Sprocket conversations. Lots of responsibilities come with a successful RUclips channel.
Sure, when I egg out a hole with an inexpert use of a tool I'm "crazy", but when Quinn does it using accuracy and correct tooling, it's "eccentric".
😂
😂
"Dramatic Banana" is a worthy entry in the game of "Band Name or Questionable Purchase".
True, so now paint the part yellow and throw it in the box marked "Not so mellow".
The fact that you use your oops’s as a teaching moment is one of the major reasons I enjoy your channel so much, your combination of humility and wit is refreshing - glad to see riches and fame have not gone to your head, lol
It's been wonderful watching this project come together. Folks that are willing to not only run scale steam locomotives but actually build them are an inspiration.
"No mistakes on my channel only pedagogical opportunities."
👌😂 you fill my heart with joy!
The stress in CRS is primarily in the skin, so it doesn't take a very heavy cut to make it bow. Glad you found the source of the bind and got it sorted successfully. That adjustable fixture is genius. "If you can't make it perfect, make it adjustable."
The best piece of advice I got from an old timer was to use round or hex bar instead of flat if you can when warp is a worry,
I really appreciate that you show your mistakes and how you approach finding the problem and how to work around or fix them. Thanks for the video.
Great start on your side rods, Quinn! Yes, getting those side rods to fit AND go around in circles at the same time is a real trick. You addressed the issues masterfully! Kozo's instructions and jigs are truly wonderful, I agree! But often, like in this case, the real issues are still an exercise for the reader. You solved this one very carefully and systematically. Wonderfully done, Quinn!
Your problem solving skills and tenacity are a big part of why I have been here for years. 🙂
I love this channel so much.
When things go wrong you show us, and it makes such a difference
wow. that's REALLY satisfying watching it work smoothly there at the end...
I was actually saddened to see how badly the letter punches misaligned. That jig is such a beautiful idea in concept.
Time to get a pantograph!
@@misterikkit Given Quinn's background and skills in the electronics format, she needs to do a project making a CNC laser marking system. She can put Veronica to work as the smarts.
Always remember, jigs make stuff repeatable, not accurate 🤣
Next project should be to make new letter punches from scratch so they fit the jig
While coming up to the arbor press my eyes kept looking for "ominous foreshadowing"... glad I can still trust you to warn us! Whew, I need a lie down after that.
Yes - I I didn’t know I could hold my breath that long.
I love this series of videos! My granddad Ben Nixon worked with a group of fellas to build 0-4-0 Reading camelback switchers, and kits/plans are still available today. I have a ton of good memories as a kid at PLS with both his switcher and Royal Scot.
I don’t think I’ve commented on one of your videos before, but I’ve been following this project the whole way and absolutely loving it. Thanks for everything
I’m here for the problems and solutions. The absolute best ways to get better at any kind of hobby/profession 🤘
I _love_ to watch your absolutly methodical aproach to problem solving!
Genius combined with genius. Future editions of the book should be boxed with your videos. At least for actual builders- I’m quite happy to have read the book and armchair the videos.
All I have to say is "Whew!"
Beautiful as always.
Thanks, and Meow to Sprocket.
I really enjoy your enthusiasm for Kozos clever fixtures and order of operations. And of course also enjoy seeing the cleverness of Kozo put to metal. :)
Oh the letter punching jig! This was what made me discover you some years ago :)
Quartering is critical. In my youth I was employed in model railroad oriented hobby shops that sold very expensive imported brass locomotive models. Mainly HO scale with a few VERY expensive models in O and S scales. There was one run of a particular locomotive where 7 out of the 10 our store had were out of quarter. When nickel silver rods a millimeter thick get bent by out of quarter drivers on an HO model, pretty is not a word you're likely to hear.
Gorgeous work as always, Quinn! Loved the jig... what a genius, Kozo. The joys of making a smaller locomotive like the A3 is, fewer side rods over all - lol! The running gear on big engines gets repetitive. My friends and I are hoping to start building a 2-4-0 soon enough, so, who knows, maybe some of your techniques might scale up. ;)
I’d offer to help, but my machine tools might be too small 😂
@@Blondihacks I'd actually been hoping to reach out to you to potentially do some of the small things! Would be a great collab.
I’m in! Drop me an email 😄
@@Blondihacksblondi. This man. This man is the man you need for stuff like this. He works at the Colorado Railroad Museum, in Golden, Colorado. He is highly experienced with trains (at least in terms of operation and mechanics), and just yes. This man is the man.
Meticulous and well-described as ever 🙌
Great job Quinn! I would have been seriously "stumped" on the quartering issue. I learn something new every day! Thanks for all that you do!!
Since "clever" in programming often means "we're going to regret this later," it's refreshing that in machinery it almost always means "clever." Although in both cases, it's usually not apparent until you have to maintain it.
"We found a novel solution that will help us meet the deadline this week, and utterly destroy us in the future" has happened far too often.
I think that's the biggest difference I've experienced between coding in school vs coding at a job. It seems almost always the better choice to have code that is easily understandable, even if it takes up more space. Sure, you could do the operation in one line, but if you break it up into four lines with descriptive variables and comments explaining why you are doing the operation in the first place, your future self will thank you.
Clever code is only clever until you find yourself having to figure out your own shenanigans a few months later.
After that, you begin to appreciate the beauty of boring, clearly laid out code.
Hopefully.
True, I have been guilty of, in the long ago past, writing code that seemed to do one thing but in effect, if you were not paying very close attention did another. Job security, I knew that if they changed that subroutine in any way the whole system would blow up. I do love case statements with custom named terms that people think are regular terms.
Evil chuckle ensues.
Very interesting. You do a great job. I'm a retired Architect, but have always loved trains. I retired when I was 52 and at the ripe old age of 65, I decided to build a 4-8-4 steam locomotive. Not having any machining experience, I was VERY intimidated, but I didn't let that stop me. The scariest part of the entire build was the quartering and constrution of the side rods. Could I do it? I trusted my mathematical skills and drove on. Miraculously, I managed to get 4 drive axles and 8 wheels quartered and machined. Miraculous in my eyes, but this only testifies that with a little perseverence and determination, anyone can realize a dream. Don't be scared to try. I'm now 71 and have a running and operational 4-8-4. I know, everyone says not to start you adventure with a 4-8-4, but at my age, I didn't have time to start with a smaller wheel arrangement and I learned something. Larger wheel arrangements should not be intimidating. The techniques are exactly the same for a short wheel arrangement vs. a longer wheel arrangement. PAY ATTENTION to the details and you can get there.
When Iwant to learn something, I often try lerning on a real thing I want to do - not some practise project. It motivates you to work through problems. Likewise, if an 4-8-4 is what you really want - go for it! It'll keep you better motivated than some smaller design you only feel moderately passionate about.
I really like your videos, as a product designer and machining enthusiast, these videos inspired me to also buy a micro lathe and milling machine, and I learned a lot of useful knowledge from your sharing. When I saw that the connection shaft between the connecting rod and the wheel was a precise fit and not a ball joint, I was worried that they would hinder the swing of the front wheel's tilt suspension system. But at the end of the video, when you turned the wheel by hand, I saw that the suspension system had The swing, it seems that the clearance of the bearings and the swing range are designed just right! Good job!
Wonderful video Quinn, thanks, helps a lot!
This was actually extremely pedagogical - having watched this video, no one will disregard the possible issues with material stress! Seeing is believing!
(I run the much smaller gauge 1 live steam size, and I actually don't want very exacting tight tolerances on axle boxes, crankpins and rods. Instead I strive for just the right amount of play, otherwise locomotives don't run smoothly.)
Great work Quinn, your process of finding the problem and the fix I think was very good. Cuttos to your patience and meticulous attention to detail.
Thanks for sharing.
I appreciate your problem solving process. Brilliant!
Nice video, especially the problem solving is higly appreciated. Respect for the whole serie and your way of showing machining parts.
Great job. Thank you 😊
It makes me totally happy to know that women like you actually exist, I know its a risky statement these days, but Ill take the chance telling you.... Thanks for giving us disillusioned old guys a believe in the future.
✌️
3:53 Yahtzee! Thanks for another video!
Nice work.
Woo-a-woooooo! All aboard!
Looking forward to seeing the linkages come together. She's turning out to be a beauty.
Dumb question/suggestion, I'm sure, but: couldn't you use the side rods to accurately set the quartering on the second side? I mean, make the side rods before locktighting the wheels onto the axles, and quarter/locktight one side "fairly accurately" (as you said earlier, it doesn't really matter if 89 or 91 degrees) using a side rod (so you wouldn't need a quartering jig nor a side rod drilling jig -- just make them together as a pair so the holes are the same distance apart), and then use the second identical rod to quarter/locktight the wheels on the other side. Seems too simple, so I'm sure I'm missing something!
I immediately thought the same thing
The "chugga chugga" is starting to become apparent.
No they go chuff chuff 😊
Great mind at work!
I can see software debugging logic going on here 🤪. Just fantastic. Thanks for letting us come along on the journey.
Always excited for the weekly upload!
An eccentric measuring stick, that is very clever.
You share a lot of valuable knowledge and skill on your channel, much appreciated.
Great job, as always. It's way less stressful watching someone else do this!
Im really sweated as the wheels blocked!
Good that you were able to fix that!
Awesome work as always
New video!! Hooray! Were inching closer to a working locomotive :)
Yay, a cold open! I've missed those!
Comedy inspiration doesn’t always strike in time for editing 😄
I do hope you removed the other wheel and crankpin, as well! The loctite on those was also compromised by the heat, and as soon as power is applied, there's a good chance it'll slip on the axle, if there's ANY slip on the wheel/rail interface of the wheel that has been freshly loctited.
Of course
The rod going banana was not a mistake, just a happy little accident. And because of this happy little accident, you showed us „normalizing“. Thank you!😉
Very good Quinn! I agree with other commenters the drilling jig is brilliant!
Bro, you are awesome. (Thats a gender neutral bro, i say bro to everyone, even my wife)
I have serious adhd and mild autism, your content both relaxes and educates me.
Its one of the reasons I've decided to try and retrain to an engineering focused career in my 30s.
Seeing your love for this craft inspires me.
Oh yea i feel u. I had to remove the retaining bolt of a 40mm udrill this week. The toolprep dude used the good green stuff and called me after he stripped the teeth of the torx head screw... It took a lot of time using the heatgun gettin all that metal hot enough to break the glue while trying not to break the extractor tool in the bolt. Burnt finger included xD
Couldn’t hit the like button enough!! This video series is the best on RUclips!
Thanks for posting
Yay!! It's Blondihacks time!!!
With one set of wheels properly quartered, I bet if you assembled the rear axle and wheels with the locktite wet and rolled it as it cured, it would force them to be in proper alignment.
Loving the progress, Quinn! Im curious whether you measured the hole spacing on the drilling jig, to compare against what it 'should' have been? I'd be interested to see just how close to perfect you ended up.
I volunteer my services as trombonist and tubist for your band Dramatic Banana (which would clearly be ska, right?)
This is the way do it in engineering song ❤❤❤❤
I’m mostly here for the band name ideas. The precision machine work is a close second.
Well.. I guess that answers the question seen so often on t-shirts during the 1970's: "Why be normal?" (Because you don't want to become a banana, of course.)
13:20 I discovered this the hard way in 1980 during my engineer education. Never forgot it though.
I am curious about the tool holder you are using with the vertical tool bit , I have not seen one like that . Can you tell me more about it ? Or is there already a clip on it ?Thanks
I do a lot of Loctite. 609, 680, and 660. It won't budge until you exceed 400F. The TDS is informative, but slightly aspirational.
I like their retaining compounds, but think their thread lockers are a joke. Nothing beats correct torque for a fastener.
NIce work BTW. You're doing fine.
Great video once again Quinn
hi Quinn, a while ago you did a video showing the Shrum Solutions Tri-fly as an alternative for a flycutter. I haven't been able to find that video again, do you know which video it is?
Amazing diagnosis and repair
Tack!
Ooo new video yay
I wait all week for this!!! 😂
@@paco_vazquez always an amazing day when there is an upload, fun stuff!
Wouldn't the stress in rolled parts be highest on the surface?
So how many miles are on it now from rolling it back and forth on the bench? 😀
Thanks Quinn. Does anyone know where I can get a copy of this book? I am having a hard time finding a place that has it in stock.
Great recovery! Very interesting content.
Love this build and that is a cool fixture. Just wondering if it wouldn't be a lot easier to set the side rails up in the mill and use pin gauges and DRO to get the correct center to center distance?
Great save on the wheels
The fixture guarantees accurate drilling as well as correct distance. It also allows for verification throughout range of suspension travel
Quinn great repair
15:22 pop!
Nice job ! It always great to see your video, but...I miss the 'Yatzzzee thing...."at the first cut... lol 😁
That's our job to add it in, same as adult language in progress. Love the channel
Trying to figure out what happened with the mis-quartered set - if one end of the axle were elevated, that would open up the angle. Perhaps there was a chip stuck in there? I doubt it, since you work with such meticulous care, but I'm otherwise stumped.
Well who cares - as you said, gettin' trainey!
I’ve wondered as well, because the quartering was too wide, which makes no sense. Only guess I have is that the wheels moved after removal from the fixture because the Loctite hadn’t set
😍
16:10 - is that kinda like our forebearers? ;)
Band Name: Dramatic Banana
Album: Stress Relief
Lead Single: More Distortion than I've Ever Seen
I would have done it differently- says everybody every time. Nice work!
Great save!
i almost had a heartattack
Would an eccentric bushing work, to get the distances correct?
Well done Quinn,hope your scalp isn’t to sore with all that head scratching.🤭🤭
Awesome save via thinking.
Since one axle can twist and the other can't, something has to flex with the side rods, right? The pins the side rods turn on won't be parallel any time the movable axle... moves. What am I missing?
The crank pins arent perfect cylinders, theyre slightly hourglass-shaped, which gives them some play in the rods
Did you press off both wheels on that axcel? You did not say. Heat surly compromised loctite on both. Great videos.
Of course
Thanks Quinn
wait, doesnt setting the eccentric bushing move the hole offcenter?
i guess the centering isnt too big a deal if youre machining more off the sides than the eccentric bushing is adjusting
Given the center marks on the axles, could you not use this distance for the jig?
Why not use the side rods to do the quartering perfectly, once you have one running?
I've never been more disappointed than at 3:53
at 3:53, EVERYONE said "Yahtzee" in their heads....
Interesting troubleshooting 🤔
Nice fix!
Great content!
Be honest now, how many hours of footage did you edit out of you pushing it back and forth? Must be very satisfying to get to this point