I'll never tire of watching threading videos, as basic a skill as it might be. There's something very satisfying about watching the threads reveal themselves as the unneeded metal surrounding them is removed. Similar to how a sculptor simply reveals the statue which always existed in the stock material.
Loved those pigtail curls coming off while threading. Very nicely done and excellently explained. Thanks for all your efforts to share your interesting work with us!
To have a job that is more of a passion and get to preserve a piece of history so our children and grandchildren can have an opportunity to experience the awesomeness of what or forefathers made with out modern science and computer engineering is what makes these videos stand out Thanks for letting us have a glimpse of your journey
Keith, I Love your videos. All the while when you were making the shoulder bolt, I kept saying to myself "Next he will bush the lever this holds on. Myself, I wold have had to to make the job complete.I guess I spent too much time as an aircraft mechanic and inspector. Gary, 73-year-old Home shop machinist in North West Arkansas.
on a 100 year old steam loco, you will be chasing worn pivots, bolts and such forever, better to fix what is broken as you go, or it will never get back on the tracks
jusb1066 I was thinking to bore the hole back to round and make the bolt to fit the bore. But, you're right, we'd be chasing every worn part on the whole engine. Sometimes you gotta just fix it and move on.
Richard Getso i believe they intend to get it back on the job, as it is a big attraction at the museum, that and they probably spend some years of budget having the boiler rebuilt, as long as parts are good enough, they can be improved later on, theres only so much you can do in the time.
I appreciate and enjoy your work on antique machinery. When I was younger I was a millwright at Nicholson File. Many of the machines were over 100 years old, all castings (even for tiny parts) and all the bolts were originally handmade... And coated with red lead when assembled.
Perfect job, no reason to dislike or complain... interrupted cuts can be rough on tooling, but all of these cuts were very reasonable. Thanks for these videos!
Nice basic machining project. I am starting to pickup on the technique of breaking corners and undercutting the end of threads. I enjoy the simple explanations delivered in a down home, country manner. Keep 'em coming Keith!
Another wealth of information to add to the collection of machining tips received from your videos. Thanks you, Keith. Can never get enough of your videos, keep them coming.
Keith, your videos have started a fiery interest in machining in me. You're clearly an upstanding dude and your videos really make me happy. Thanks very much!
One of my favorite episodes of all your videos, was when you explained all of the levers, dials, and valves of the cab of your 1917 Vulcan Iron Works steam locomotive and then gave us a ride around the perimeter of the Museum grounds in it. In that video, I saw you manipulate that black lever, but you had failed to tell us what it was or used for. At the time, I had figured it to be the lever for the reverse-forward mechanism, but several times while we were in motion, I saw you adjusting it, moving it with no effect of changing direction. In THIS video, you told us what I had guessed it to be AND you said it was ALSO used to adjust the steam valves feeding the cylinders. You unknowingly answered my question with this video. LOL AND I can't understand how ANYONE could "dislike" your videos.
Thanks for sharing Keith. That bolt was kind of sorry with chunks missing and that taper. No wonder the wrench slipped. Anyway, this one is sure to last another 100 years. Thanks for posting.
Hi Keith ! Oh, I like watching these coarse threads been cut so nicely as you did here - nice work ! As I remember you live in the area where the storm had its pathway - hope you came through without any damages.
Nope they're not ever fully 'done'. All the heavy moving parts and the massive forces those large and heavy parts are subjected to in steam loco service, every single component on a steam loco gets the proverbial crap beaten out of it every time a fire is put in the firebox, steam pressure is raised, the reversing lever is put in the corner, the brakes released, and the throttle opened.
OnlyTheEd Uh-huh, I did watch the two films of the seminar session Ed Dickens gave in March of this year in Colorado that extensively covered a lot of the boiler repair efforts that were undertaken on 844, and the video updates from the Steam Crew that Union Pacific posted. Was the most extensive work 844 had had done on her since the last time she was 'shopped' in the 1950's right, in the twilight of her revenue-earning days? My eyes were bugging out at some of the boiler issues Ed and his gang had to tackle, as I've learned a lot about boiler upkeep from an uncle who cleans them for a living.
One of the great advantages of being a machinist; Special fasteners on an antique application. I still am wanting to get my little Atlas lathe up and working on some Ham radio antenna apps. Hobby only for me so don't worry about me taking over the RUclips video scene. Greg
Interesting that it's called a Johnson bar because semi trucks have something called a Johnson bar, but it's just under the steering wheel and it applies the trailer service brakes. I used it a lot for sliding my tandems. I imagine it's a holdover from the days before trailers had spring brakes.
The work is never "done" on an old locomotive, eh? Nice job on the replacement part and also knowing when to draw the line on the project. Hope you are well and the shop is coming along. Sincerely, Tom Z
Nice job! If you have the time maybe you should try and put in a brass bushing in it would have a better fit and would prevent seizing and contribute to the longevity of the part!
So The Multimedia Man so the original 99 year old blot did not last long enough? Sure you could go OTT but it's as much knowing where to make improvements on the original and where to replicate.
In hindsight it would have been nice to ream the reversing lever hole out a little and make your bolt a little bigger. Still it will do the job and last a log time so good job!
Have you thought on re-making the "Johnson's bar" at some point? That way, you have no need to bore out the hole for a bronze bushing in a couple years.
Keith, Great as always. Why not put the date and your name on the top of the bolt? Old house restoration work often leaves writing under wall paper, newspapers of the date inside wall etc.
Hi mate. It looked like a good footrest for some of the pilots when driving the locomotive for days on end. I don't know if it's possible, but that's what it looks like to me.
Great to see a bit more of the work going into putting the 0-4-0T Vulcan Iron Works engine back in service! 'Armstrong' reverser lever! Its probably a good guess that when the engine is moving and you want to change the reverser notching on it, you MUST close the throttle to just being a crack open, to keep the lever from being yanked outta your hands when you unlock it to move it, right?
There's only one 'reversing lever' used in a conventional steam locomotive and its located on whichever side the engineer/driver controls the brakes and throttle from, so only one replacement pivoting bolt needed to be made.
I noticed you faced under the head from outside to inside. Normally I would face from inside to outside without moving the tool. So, in effect using the other edge of the insert. Is facing from outside to inside a better practice?
When one is doing an intermittent cut, like the hex, is it harder on carbide inserts than perhaps using a HHS tool bit. If that is correct, do you have any suggestions on cutting the hex? On some things I have made, like the bolt, I heat them up and dip into old motor oil. It gives them a nice dark blue finish, and maybe helps resist rust (?).
Another great video , but i do have a question why not bor a few thousandths out the eye on the bar and make the shoulder of the bolt a few thou larger in my miind should have taken all the slop out
That would reduce the material in the pivoting area of the johnson bar to withstand the loads put on it as the locomotive is used. This bar controls the forward and backward direction of the locomotive as well as how much steam is used while the loco is moving. If this area breaks then the bar has to be remade or at least this part of the bar has to be made and attached. The loco won't work without it. This bar moves a little each revolution of the wheels as the loco moves and is subjected to large stresses.
As always Keith, I greatly enjoy your videos. Just a question, do you ever try to apply a finish to bare metal to try to keep new parts from standing out from the original patina?
Keith, nice job but I have a question; looking at the swarf it appears you cut the threads using the cross slid rather than the compound, did I see this correctly? They looked almost “V” like…..? Love your videos, keep it up, Thanks!
G'day Keith really enjoyed watching you make this part for the old girl. Just one question what do you use for cutting oil? Look forward to the next video kind regards John from Tasmania
What is the purpose of the relief cut on the bolt? It almost seems like it would act as a shear point if the bolt was over torqued and I don't think that would be a good place for a shear point.
There are occasions where what you describe is required. One that I did long ago are tapered stub acme oil well drill pipe threads. The requirement is that the the tapered threads lock up at the same instant the joint faces meet. It has to be held closely otherwise it be near impossible to unscrew each segment of the drill pipe as it is withdrawn from the well. I had the good fortune to do this work on a Mazak CNC lathe so that the threading tool pulled out of the work at the same place every time. When the thread gage was hand tightened on the work, a feeler gage would be used to measure the gap between the joint faces for the correct dimension so that when wrung together, the threaded joint could still be disassembled. Manual oilfield lathes often had an automatic kick-out to pull the threading tool out of the work and stop the feed. CNC had the advantage of easily making adjustments and the rapidity with which the threads could be cut.
Think you took a lot more care than the original machinist, though to be fair he likely had an order to make 50 of those bolts, had a half day to do it all in, and still had to make the hex stock out of some cold rolled steel rod that was in the shop, and this was one of 50 orders for the month to do. The repair with braze was very likely something I would also do, much quicker and can be done without a lathe, just using a file and sandpaper to get the rough shape. Quick repair would have just been to use a steel shim and grease, would have gotten them moving back to the yard fast, and then do the pivot with the braze, rather than spend a few days out in the open waiting for a repair to be done. Undo bolt, grab a tin can and the ever present tinmans cutters and 5 minutes later you have a bushing to fit and you are running within minutes and still have near a full head of steam.
The dimension that you for slack in the bushing is too little to bush it but you could knerl the bore and I deffinately would put in a lubrication fitting course with lithium grease it should last another 200 years as is.
It doesn't mean anything. There are some strange characters that enjoy putting thumbs down on videos they don't even watch. They never make any comments about what they don't like either. Life on the planet.
Some folks are concerned that you didn't make a precision fit for the part. I figure in the day that locomotive was built, with all that iron and heat, if everything had been fit properly, the whole thing would have seized up in about 45 min. Either that or you would have had grease or oiling points on every fitting and joint on the engine and spent a good deal of time re-lubricating during a trip. Since the part you made won't last much more than 150 years, you could have done better (that's a joke).
I apologize for making a criticizing comment however a dark object against a dark background does not show up well. Even a sheet of copy paper would work well. Thank you.
I'll never tire of watching threading videos, as basic a skill as it might be. There's something very satisfying about watching the threads reveal themselves as the unneeded metal surrounding them is removed. Similar to how a sculptor simply reveals the statue which always existed in the stock material.
I concur. A thread (and to thread) is powerful in that a practical and elegant bit of sophisticated mechanism is realized almost instantaneously.
Loved those pigtail curls coming off while threading. Very nicely done and excellently explained. Thanks for all your efforts to share your interesting work with us!
To have a job that is more of a passion and get to preserve a piece of history so our children and grandchildren can have an opportunity to experience the awesomeness of what or forefathers made with out modern science and computer engineering is what makes these videos stand out
Thanks for letting us have a glimpse of your journey
Keith, I Love your videos. All the while when you were making the shoulder bolt, I kept saying to myself "Next he will bush the lever this holds on. Myself, I wold have had to to make the job complete.I guess I spent too much time as an aircraft mechanic and inspector.
Gary, 73-year-old Home shop machinist in North West Arkansas.
Gary Jones:
Yup, probably only last another 99 years... :>)
on a 100 year old steam loco, you will be chasing worn pivots, bolts and such forever, better to fix what is broken as you go, or it will never get back on the tracks
jusb1066 I was thinking to bore the hole back to round and make the bolt to fit the bore. But, you're right, we'd be chasing every worn part on the whole engine. Sometimes you gotta just fix it and move on.
Richard Getso
i believe they intend to get it back on the job, as it is a big attraction at the museum, that and they probably spend some years of budget having the boiler rebuilt, as long as parts are good enough, they can be improved later on, theres only so much you can do in the time.
I appreciate and enjoy your work on antique machinery. When I was younger I was a millwright at Nicholson File. Many of the machines were over 100 years old, all castings (even for tiny parts) and all the bolts were originally handmade... And coated with red lead when assembled.
Perfect job, no reason to dislike or complain... interrupted cuts can be rough on tooling, but all of these cuts were very reasonable. Thanks for these videos!
Nice basic machining project. I am starting to pickup on the technique of breaking corners and undercutting the end of threads. I enjoy the simple explanations delivered in a down home, country manner. Keep 'em coming Keith!
Another wealth of information to add to the collection of machining tips received from your videos. Thanks you, Keith. Can never get enough of your videos, keep them coming.
Nicely done.
Folk seldom appreciate how much expertise is required to make even the simplest things - like a bolt.
Thanks Keith,
I like your "common sense" approach and I never get tired of watching you cut threads.
Keith, your videos have started a fiery interest in machining in me. You're clearly an upstanding dude and your videos really make me happy. Thanks very much!
Having that nice hex stock sure saved a lot of time!
One of my favorite episodes of all your videos, was when you explained all of the levers, dials, and valves of the cab of your 1917 Vulcan Iron Works steam locomotive and then gave us a ride around the perimeter of the Museum grounds in it. In that video, I saw you manipulate that black lever, but you had failed to tell us what it was or used for. At the time, I had figured it to be the lever for the reverse-forward mechanism, but several times while we were in motion, I saw you adjusting it, moving it with no effect of changing direction. In THIS video, you told us what I had guessed it to be AND you said it was ALSO used to adjust the steam valves feeding the cylinders. You unknowingly answered my question with this video. LOL AND I can't understand how ANYONE could "dislike" your videos.
Always nice to see work on the Vulcan.
Fantastic! How cool is it to look at that old locomotive and see all the parts you MADE BY HAND? Mind. Blown.
Thanks for sharing Keith. That bolt was kind of sorry with chunks missing and that taper. No wonder the wrench slipped. Anyway, this one is sure to last another 100 years. Thanks for posting.
I like all of the formats of your vids, but this is the bread and butter that made me a subscriber.
Nice work
Replacing aged parts, rewarding.
Great video Keith!
Thanks Keith another great job
Nice work Keith. Best wishes from Cornwall, England.
Nice video, wish you could find more worn parts to make, and of course make a video of all of these parts being made. Thank you Keith! Edgar
a fun and easy project threading is very satisfying I am envious of your access to good stock to start with
Another good job Mr. Rucker.
Love your videos! They bring back memories of when I worked with a lathe, milling machine....etc....Thanks!
Hello Keith,Great work and always nice to see some lathe work.Looking forward to the next video and many greetings from Roel.
Absolutely LOVED this video, Keith. This is the stuff i'm really into.
Hi Keith !
Oh, I like watching these coarse threads been cut so nicely as you did here - nice work !
As I remember you live in the area where the storm had its pathway - hope you came through without any damages.
Obviously a locomotives repairs are never done. Nice video, thanks.
Nope they're not ever fully 'done'. All the heavy moving parts and the massive forces those large and heavy parts are subjected to in steam loco service, every single component on a steam loco gets the proverbial crap beaten out of it every time a fire is put in the firebox, steam pressure is raised, the reversing lever is put in the corner, the brakes released, and the throttle opened.
If you get the time, watch the rebuild of the Union Pacific's UP844. It was pretty much 80% or more of new materials went in to the re-build.
OnlyTheEd Uh-huh, I did watch the two films of the seminar session Ed Dickens gave in March of this year in Colorado that extensively covered a lot of the boiler repair efforts that were undertaken on 844, and the video updates from the Steam Crew that Union Pacific posted. Was the most extensive work 844 had had done on her since the last time she was 'shopped' in the 1950's right, in the twilight of her revenue-earning days? My eyes were bugging out at some of the boiler issues Ed and his gang had to tackle, as I've learned a lot about boiler upkeep from an uncle who cleans them for a living.
One of the great advantages of being a machinist; Special fasteners on an antique application. I still am wanting to get my little Atlas lathe up and working on some Ham radio antenna apps. Hobby only for me so don't worry about me taking over the RUclips video scene. Greg
Once you have a lathe you'll won't believe that you were able to live without it.
I learn something every single time! thank you Sir
Interesting that it's called a Johnson bar because semi trucks have something called a Johnson bar, but it's just under the steering wheel and it applies the trailer service brakes. I used it a lot for sliding my tandems. I imagine it's a holdover from the days before trailers had spring brakes.
en.wikipedia.org/wiki/Johnson_bar_(vehicle)
Have been using those 2501's since they came out. Seco is my favorite brand.
Nice vid Keith, I think my first ever threading project on the lathe was a shoulder bolt similar to this one, thumbs up!
Nice vid Keith......always good stuff from you.
The work is never "done" on an old locomotive, eh? Nice job on the replacement part and also knowing when to draw the line on the project. Hope you are well and the shop is coming along.
Sincerely,
Tom Z
THANK YOU...for sharing.
hi Keith, pour a babbit on the lever. useful and you get to use your smelter/ oven thing you built a while back.
Another great Moment in turning some thing from Nothing to something useful Keith :) keep up the Great work Mate
Interesting process. Thank you very much.
Another great video! Thank you!
Nice job! If you have the time maybe you should try and put in a brass bushing in it would have a better fit and would prevent seizing and contribute to the longevity of the part!
So The Multimedia Man so the original 99 year old blot did not last long enough?
Sure you could go OTT but it's as much knowing where to make improvements on the original and where to replicate.
I can appreciate the desire to replace the original bolt. Looks like the original was removed many, many times.
A simple project but interesting.
In hindsight it would have been nice to ream the reversing lever hole out a little and make your bolt a little bigger. Still it will do the job and last a log time so good job!
Great stuff, thanks Keith.
What kind of maniac gives Keith's videos a thumbs down?
an idiot plain and simple.
Excellent video! I love these types of projects.... Here's the problem. ..this is the solution. .....
Have you thought on re-making the "Johnson's bar" at some point? That way, you have no need to bore out the hole for a bronze bushing in a couple years.
thumbs up keith , Good job man !
The Museum is very lucky to have you as a volunteer. Keep up the good work! How is your new shop coming along. Besr regards from Ron across the pond.
Awesomeness Extreme
love this channel so interesting keep up the videos :)
Keith,
Great as always.
Why not put the date and your name on the top of the bolt?
Old house restoration work often leaves writing under wall paper,
newspapers of the date inside wall etc.
Could have reamed the hole out some and made the bold over size. Adding a grease fitting would help or is it easy to oil.
Hi mate. It looked like a good footrest for some of the pilots when driving the locomotive for days on end. I don't know if it's possible, but that's what it looks like to me.
Great to see a bit more of the work going into putting the 0-4-0T Vulcan Iron Works engine back in service! 'Armstrong' reverser lever! Its probably a good guess that when the engine is moving and you want to change the reverser notching on it, you MUST close the throttle to just being a crack open, to keep the lever from being yanked outta your hands when you unlock it to move it, right?
Correct. Or at least a very good idea. Been there and done that.
nice job
Would it be worth drilling a small Cross hole for a grease fitting to help reduce further wear?
When you are recreating parts like that, do you document the specs you made the part to for future maintainers?
In the thermal power industry all that stuff is recorded in a log book that stays with the plant.
If someone asks about the loose fit, just tell them it's for expansion because of the heat :D
TIdy small-scale project executed swiftly and expertly. Probably it was a good time, however, to make TWO, one for the "other side" or stock....???
Stock?
that bolt as stated is off a 99 year old machine,bolt likely same age. Lever is single item,There is no matching other side.
There's only one 'reversing lever' used in a conventional steam locomotive and its located on whichever side the engineer/driver controls the brakes and throttle from, so only one replacement pivoting bolt needed to be made.
That poor original bolt sure had a hard life!
I noticed you faced under the head from outside to inside. Normally I would face from inside to outside without moving the tool. So, in effect using the other edge of the insert. Is facing from outside to inside a better practice?
When one is doing an intermittent cut, like the hex, is it harder on carbide inserts than perhaps using a HHS tool bit. If that is correct, do you have any suggestions on cutting the hex?
On some things I have made, like the bolt, I heat them up and dip into old motor oil. It gives them a nice dark blue finish, and maybe helps resist rust (?).
Another great video , but i do have a question why not bor a few thousandths out the eye on the bar and make the shoulder of the bolt a few thou larger in my miind should have taken all the slop out
That would reduce the material in the pivoting area of the johnson bar to withstand the loads put on it as the locomotive is used. This bar controls the forward and backward direction of the locomotive as well as how much steam is used while the loco is moving. If this area breaks then the bar has to be remade or at least this part of the bar has to be made and attached. The loco won't work without it. This bar moves a little each revolution of the wheels as the loco moves and is subjected to large stresses.
Ok
As always Keith, I greatly enjoy your videos. Just a question, do you ever try to apply a finish to bare metal to try to keep new parts from standing out from the original patina?
Keith, nice job but I have a question; looking at the swarf it appears you cut the threads using the cross slid rather than the compound, did I see this correctly? They looked almost “V” like…..? Love your videos, keep it up, Thanks!
Hi Keith...really pretty threads. Leaded screw machine stock?
If Keith keeps making parts, he'll have a new locomotive pretty soon.
Are you going to apply any "finish" to the bolt? So that it would match the black oxide of the other parts?
I'm surprised to see a hex bolt on such an old machine.
Thanks, nice video. What was the material?
My only complaint -- no pictures of the locomotive as it's being reassembled.
G'day Keith really enjoyed watching you make this part for the old girl. Just one question what do you use for cutting oil? Look forward to the next video kind regards John from Tasmania
What is the purpose of the relief cut on the bolt? It almost seems like it would act as a shear point if the bolt was over torqued and I don't think that would be a good place for a shear point.
There are occasions where what you describe is required. One that I did long ago are tapered stub acme oil well drill pipe threads. The requirement is that the the tapered threads lock up at the same instant the joint faces meet. It has to be held closely otherwise it be near impossible to unscrew each segment of the drill pipe as it is withdrawn from the well. I had the good fortune to do this work on a Mazak CNC lathe so that the threading tool pulled out of the work at the same place every time. When the thread gage was hand tightened on the work, a feeler gage would be used to measure the gap between the joint faces for the correct dimension so that when wrung together, the threaded joint could still be disassembled.
Manual oilfield lathes often had an automatic kick-out to pull the threading tool out of the work and stop the feed. CNC had the advantage of easily making adjustments and the rapidity with which the threads could be cut.
Thanks Keith - I always learn something from your videos
Isn't mild steel a little soft for this purpose?? Rod
Nice!
very good job Keith. but stop making it look so easy lol. HOW IS THE SHOP GOING. I HAVENT SEEN AN UPDATE YET, LOL.
My garage mechanic told me a shoulder bolt is one that's left over after you reassembled the engine, so you throw it over your shoulder.
Looked fine to me
Thumbs up,,, good video.. 👍👍👍💪💪💪
Think you took a lot more care than the original machinist, though to be fair he likely had an order to make 50 of those bolts, had a half day to do it all in, and still had to make the hex stock out of some cold rolled steel rod that was in the shop, and this was one of 50 orders for the month to do. The repair with braze was very likely something I would also do, much quicker and can be done without a lathe, just using a file and sandpaper to get the rough shape.
Quick repair would have just been to use a steel shim and grease, would have gotten them moving back to the yard fast, and then do the pivot with the braze, rather than spend a few days out in the open waiting for a repair to be done. Undo bolt, grab a tin can and the ever present tinmans cutters and 5 minutes later you have a bushing to fit and you are running within minutes and still have near a full head of steam.
The dimension that you for slack in the bushing is too little to bush it but you could knerl the bore and I deffinately would put in a lubrication fitting course with lithium grease it should last another 200 years as is.
Ah, the good old Armstrong power reverser.
Couldn't care why they hate but I love watching this it like meditation I don't even hear my wife talking.
ah ha it's the wife's thumbs dowm
hi keith
How about building the pivot LEVER HOLE up with BRAZING.?.?.?
The person who worked on it before probably was not a machinist, they just built it up and then filed it to fit.
How will you harden that bolt?
Great work!
....13
you must love you're job wow wow
I don't think this is his job. He volunteers for the museum.
Will what ever it's fantastic
Too bad you didn't have the lever before starting the job. Maybe a little oversize on the bolt and a slight ream on the lever. I just like tight fits.
Don't understand the dislike currently, what's not to like. Some salty people out there.
It doesn't mean anything. There are some strange characters that enjoy putting thumbs down on videos they don't even watch. They never make any comments about what they don't like either. Life on the planet.
i agree
Because this is the internet
Dinxsy or a mis click no one picked up on
Just unhappy people.
Great video as always! But why not part it off instead of using the ban saw? You'll kill two birds with one stone
Did anybody see the skunk run across the shop floor?
Some folks are concerned that you didn't make a precision fit for the part. I figure in the day that locomotive was built, with all that iron and heat, if everything had been fit properly, the whole thing would have seized up in about 45 min. Either that or you would have had grease or oiling points on every fitting and joint on the engine and spent a good deal of time re-lubricating during a trip. Since the part you made won't last much more than 150 years, you could have done better (that's a joke).
The negative responses are probably from folks who are just jealous because they do not have their own locomotive!
Mr Rucker you like to share who's getting your vote in the upcoming election? Love your vids!
oh thats never good to share that, always leads to someone not being happy
You're right, just curious that's all. I'm from the Netherlands so no dog in the race. Who's getting your vote? :p
Emma, if anyone deserves it she does.
JackTekkel
luckily im from UK , so i dont have to choose either, honestly glad i dont have to
With you on that one my friend. It's choosing between two evils.
I apologize for making a criticizing comment however a dark object against a dark background does not show up well. Even a sheet of copy paper would work well. Thank you.