Scraping in a dovetail - detailed
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- Опубліковано 9 сер 2010
- Here, I show in detail upon request how to scrape inside a dovetail. And you see what crap is coming out of the "happy elefant fart, tractor and fortune cookies factory" in China.
- Наука та технологія
Great video, thank you for showing everything in detail. All the best
@Axbent
The cross slide had been measure by the client at site and I was told that it is off my a certain amount. So I only had to a) get some repeatable reference and then b) had to rotate the guide by the tad that I was told. Client was happy with the result. I don't want to promote this as the best way, but it was the best doable way (except shipping the bed; $).
I worked with two tools: A manual scraper and an electric one, called BIAX. I think the BIAX can be seen in the Myford #3 video
Thank you very much Nick. You are the one who introduced me to scraping.
Thank you Nick you patience and precision is inspirational.
Alan
They don't produce working tools, they only produce contraptions that look like tools.
If they could build good tools, they would be available.
Would you like to explain how do you set up and ink up the area to be scraped to make sure it stays aligned with the rest of the lathe?
Thank you SO MUCH!! I really want to learn to scrape! I'm going to check out more of your videos!!
Tips for going about learning to scrape when I'm new to metal working in general? Great work as usual! I've seen a few of your videos now
Perfect guide - super workmanship!
@Axbent If you look at the guide for the crossslide, it has to be perpendicular to the guide for the bed. Now I don't have the bed, so I need some other reference that is more or less parallel to the crossslide. That reference was the granite angle. Now I measure the distance from angle to dovetail at the front and set the dial to zero. Second measure from angle to rear of the dovetail. That gives some value (in this case it was IIRC 0.17 mm). I know that the cross slide has to be rotated ...
great job on this video bud, your camera work is pretty good at showing in focus, the errors to be repaired, tnx again
thanks for making this video- its been very helpful- great job!
Parabéns pelo vídeo. Executei esse trabalho por cinquenta e cinco anos em máquinas de pequeno médio e grandes portes.Maquinas vom tolerâncias de milésimos de milímetros. Bom ver esse trabalho para milhares de visiluacoes.
@Axbent ... by amount X (0.035mm) So I scrape the dovetail and shift the tilted plane by guessing and measuring by the desired amount. That amount is reached when I measure again and the difference between front and rear is 0.25mm (see notes on the part).
The prism is needed for marking the tilted sides of the lower part. After that, the lower part's tilted sides are the master for the upper part. Look at my video "Scraping in a lathe's top slide", it describes the sequence in detail.
HTH!
How do you know that the Granite triangle you used to measure the V-ways was perpendicular to the bed of the lathe? Or rather perpendicular to the underside of the cross slide carraige ways? And when you took that measurement and you were using the dowel pin how would you know if it was the flatness or the angled ways that were out? Thanks.
How much work was this to do, and what tools did you all use? Also, what happens if you make a mistake? What do you do then?
It's amazing that you have all these precise meteorology instruments but when you buy a mill, you get the cheapest money can buy? But THANK YOU for making the video! It is the first one I watched on scraping, and answered a lot of questions I had come up with from only reading about scraping. I plan on watching all your scraping videos...
Well done mate , a good job
Hello Nick, three additional questions:
1. The stone to remove the burr, is it silicon carbide?
2. What is the granulation size?
3. How it is possible to get a stone as seen at 7:09 in a v-shaped form?
Teflon coating is a standard after-market practice, especially among hobbyist machines. Iron on iron is considered non-feasible for extended use; just a trend here in China. People buy low-end lathe/mill, first thing they do is an after-market teflon and scraping. Industrial class or CNC tools come with teflon factory stock.
Great work ! I can see the craftmanship of a seasoned machinist. One question if I may: if you were to choose between retrofitting (scraping in) an old lathe, say 1,5 m long travel, and building a new one ,with the bed made out of UHPC (or epoxy concrete) , with linear guideways, what would you choose ? (assuming you would have all the tools&gigs needed, that the concrete lathe would be prepared for CNC mode and no "manual" threading on the bed would be necessary, and also budget would not be a constraint). Would you see a problem in having linear guideways, as opposed to prismatic bedways, as far as cutting forces tending to tilt the carriage over is concerned ? Thank you for the mental push-up exercise employed in answering this question.
Interesting question. The linear guide are very common in machines from companies like Haas. They like them because it is much easier to get them aligned properly and also when things get worn too far then it's a simple matter to just change the parts out.
I tried pull scraping, sometimes I have to do it. But I don't feel comfortable with it. Pushing seems more natural to me and seems to be faster (maybe lack of training).
But if anyone feels more comfortable with pulling, it is OK.
OTOH, the finish looks different, and that might be what one wants.
great vid nick, i think my 15 lb chi slide vise will be 5 lbs when done scrapping,lol thnx 4 the vid
Thanks for your kind comments about scraping.
But bitching about my MAHO 700 is not OK. :-)
She milled all the patterns for my castings.
The scraping vids were made with tools that are NOT mine, except for the Myford grinder.
@phibieb What country are you from? I mean, if I tell you that I bought it at Hoffman Munich, is that of any help?
Any Sandvik dealer should have them. But there are other manufacturers.
Yes, that's an oil channel. It was milled by the manufacturer. And yes, it helps.
I helped a friend scraping in a Optimum (I call them Pessimum) BF 20L. It's simply a cheap construction with bad craftsmanship.
Example: After scraping a guide, we screwed in a grease nipple. After that, he had to rescrape that guide.
I'm near Munich. I could show you the basics (minus metrology) in two days. But you'll break down after one day. :-)
@princeigorash
Forums like HomeShopMachinist of PracticalMachinist talk about scraping. You'll find information there.
Two polished surfaces adhere to each other, they don't glide very well. Oil pockets at one side are essential for good tribology.
@MrDeepwoodtickles
Well done!
The spotting seen here is not an exception, it is the standard for the Chinese crap you get. No matter what the importer tries to tell you.
@petsatcom I don't know the manufacturer, and am not sure about the importer. But yes, that's about the average "quality" you get.
My mill weights 3 tons, my lathe 2 tons, my cylindrical grinder 0.8 tons, my T&C grinder 0.9 tons and I do have about 3 tons in shapers.
Complexity (or lack thereof) of G-code or manual ops is not related to the weight of the tool.
Hmm, we might have a misunderstanding, glad you put in a :-). Maybe after I have time to finish watching the videos I'll understand better. If those scraping tools are not yours, you sure know how to use them! I look forward to trying to scrape for real, not just read and watch. I have some used homemade scrapers off ebay, and I'm trying to beg borrow or steal what I need to get them sharp again.
How do you blue the inside of the dovetail when you can't fit a parallel or plate in the gap?
You Blue the outside piece with the surface plate, once that part is scraped flat you slide it against the inside part and use it as your reference
Great vid,
Umm ... depends. :-)
With softer cast iron (as in this case), maybe every three to 5 passes. Hard CI might need re-shapening after every pass.
hello; had to laugh on your comments. bulls eye! IMHO. i have a chinese built lathe labelled for marketing by a tool company in 1 of 2 north american countries(do not know the legalities of commenting here but rather not be sued). this video gives me hope i can rectify my carriage, crossslide, issues . my tailstock and carrige have been scraped to the ways with a mini grinder. please continue with the videos. your knowledge can save us from the fate of this junk from china.
I would love to see you do one of the optiumum weiss bf20 style machines. They are so popular all over the world and so many people work on various upgrades to them but the one thing they don't do is scrape them for better accuracy. Im In Wien and depending on where you are I could load up mine in the car(retrofitted to CNC) but id take it apart first and we could do a video of doing some of it. More than that Id love to learn the skill from you for a few days master:)
I am interested to learn basic scraping. what model manual scrapper is that? where can they be purchased.
salam kenal om mau tanya nama pisaunya apa itu om
I knew how much the cross slide was off in perpendicularity. Owner measured it and gave me the numbers.
Hello.
If I may ask...where I can find detailed information about scraping.It may sound stupid...but why not to machine on grinding machine?Wich is the difference between a scrapped surface and a polished surface? The scraped surfaces are they mating together during operation or there is an oil film between them?Can this be done on larger machines (lathes wich can machine pieces 1-2 m length )?
Thank You.
P.S.: I don't know nothing about scrapping.
That's almost 2 years in the past, so I don't remember any numbers. Or complaints. :-)
But I do remember that he was quite pi**ed with the rest of the lathe that he converted to CNC.
I was also considering attaching something like NSK linear rails on some nicer steel sitting on the current slideways.
But it still wouldn't help if I cant get those steel supports nice and flat. I think that would make for a fairly nice machine given that the ball screws and steppers I have seem to do a pretty good job already
BTW I also sent you a Private message:)
nice job
Sorry, misunderstanding!
The scraping tools and metrology tools sure are all mine. But the machines I showed scraping aren't mine, except for the Myford. My mill, the MAHO, was cheap, because she didn't work. But now she works again.
Kitty approved.
I'm starting to think when you get evolved with scraping it becomes a drug. Addictive to scrape and check until you nut it down to the at least tenth in your capability. Closest I ever worked was 50 mill on seamless can tooling OD/ID grinding with diamond wheels.
Nice of you to support friendly Chinese industry, but any way, I was wondering if you ever tried pull scraping. Some Frenchmen or Swiss experts posted a video depicting it. In manuals it is only alluded to as a possibility. After all, pushing a scraper for hours, even with a body stroke, gets tiring and I am too cheap to buy a Biax.
Well, it is not hard, but it is a long road. I suggest finding someone who shows it to you.
Re the ballpoint ink: That will be an incredible mess to get it off your hands, clothes, tools.
Buy a spotting blue and be happy.
Question what is he doing at 7:26min? Converting what to 60degrees? Thanks
The prism (for touching). I only had one in a convienient length with (IIRC) 55°. There is no picture of the prism in this video.
Did this answer your question?
MuellerNick ahh yes i understand! Thank you for great video sir 👍🏽
Good, thanks.
Nick: Thanks for the lesson. Who is the lathe Manufacturer?
I guess this is typical quality?
Hallo Nick, kannst du mir bitte eine Quelle nennen, wo ich die Hartmetallklingen beziehen kann? Danke!
Die Klingen gibt es bei Hofmann Werkzeuge. Da kann man inzwischen auch als Privater bestellen.
@@MuellerNick Vielen Dank!
That was fun! One comment though, if you pay enough the Chinese will do a very fine quality scraping. They don't get paid enough to even do the quality you show here at the start, we are talking about consumer class products, not industrial. Have you seen their higher quality scraped goods?
I don't believe that put scrape mark there just to pretend. Most likely the casting was rushed to assembly without proper stress relief so it moved after scaped in.
Nah they fake it like hell. Just got home a 13X24 (my first lathe) the carriage had Rulon or Turcite (I want to believe) and it looks like it was hit with an angle grinder. In my opinion just glued would of worked better, but ignorant people go and see that and think is precision work.
If you can't see it it will be a bad surface, but the lathe is cheap and with good care and a bit patience it can be improved. I wouldn't recommend it to anyone for business unless you don't need high accuracy and precision but hobbyist is fine. You get what you pay for, mine is way better than the 10 X 22 I saw at the store and I didn't even looked at the 7 X 12 just crap.
@hla27b
One of the nicest compliments I could get! But don't curse at me if it takes longer than expected. ;-)
A rather edgy video. But cutting edge stuff. And yes the Chinese both sail and sell Junk. Thanks for the pointers, I am working on a really cheap Chinese X / Y table for a drill press and am facing ways that clearly have a taper from end to end.
that should scrape really easy... since its cast pot metal, lead, zinc etc.
Dovetails must the worst part in scraping, super difficult.
you are my hero! hammer in hand america will stand.
if you wanted something good just get a surface grinder and call it a day once you cut the angle on the wheel it would be done just have to make and grind some spacers and it would be more accurate. or just remake the top end.
Surface grinding is no substitute for scraping. There is no place for oil to go with a surface ground as opposed to one that is scraped, hence why all top end machines are done that way and not surface ground.
AldoSchmedack Thats correct aldo, the two surfaces can not be perfectly flat or no oil to fill in emtpy spaces.
Have you come across the knock-offs of Swiss Multifix? Even used original Swiss sets are pricy and I should like to get something more practical than a lantern tool post and more flexible than a square turret for my ancient lathe after it is rebuilt. Any thoughts or comments would be greatly appreciated.
Пусть будет комментарий на русском)
Да не в Китае дело. Основная проблема в отсутствии у этих людей возврата товара, что и приводит к такому отношению к работе
it's scrap now
*GASP* China quality
8:43 ........meow! ha ha haa
набери - Черновое шабрение
What is purposes scraping?
The purpose is to educate people to read comments and to further investigate by themselfes if they are interested.
The purpose of my videos is not to provoke dumb questions. They do exist!
@@MuellerNick Hello Sir,
Nice video on scraping it was really learn full, I have a lot of questions but I will ask one.
When scraping the male and female dovetails of a machine tool, would this not ruin the fit between them that was made in the original factory the machine tool came out of?
The scraping removes after all metal, am I missing something fundamental or is it correct that the fit between the male and female dovetails becomes bigger and there is play between them after the scraping, and how is this solved, is there a solution?
I may have asked more than one question,
Kind regards.
@@mjmj5224 Yes you are right, but you missed one important part: The "gap" is adjusted / taken out by the gib. The gib is a tapered flat bar with an adjusting screw.
@@MuellerNick Thank you for your answer.
So the gib presses as it were the dovetail to one side all the while you would be feeding the compound inwards and outwards (to turn diameters, not across I mean to turn lengths).
And for example if I wanted to scrape a lathes' bed could I do this by running over the lathe bed with a perfectly flat granite block about the size of my palm over the ways (with blueing applied ofcourse on the master block).
Would this show me the high spots on my lathes' bed? Or is this not correct.
Will one side of my lathes' bed be exactly the same 'height' as the other side if I scraped them perfectly flat.
Thank you for your efforts in answering my questions.
@@mjmj5224 re gib: Yes
Re bed: That won't work! Your master needs to be as long as the work (complicated if a bit shorter, longer is no problem). You can use a precision ruler (I think I use one in my Myford videos). But scraping a bed is complicated.
Re height: No, but you have to make sure both ways are not twisted (check with a precision level, shown in my Myfor video)
what is the purpose of hand scraping
It uses less energy than power scraping. So the purpose is to save the planet.
It is to provide a pathway for oil to move about on the ways, and it is far easier and cheaper for a home shop to do compared to a machine scraper that can cost thousands. Good question!
@Tombfyre80
No sorry, there is no detailed (or any) description how to read the blue. I thought about making a video about that for several times. But it would require some animation tools I don't have. I tried to collect shots of clear readings, but that also failed.
Maybe once I'll come up with a description. As soon as you understand what the blue does, it's easy to draw your own conclusions. I never found a clear explanation. Maybe, I'll try it with some sketches.
Total bullshit, whats you master? An unscraped, un true cross slide? Cant read the "blue"? You know absolutely NOTHING about scraping nor machine rebuilding. Oh, heads up on yer method on 90'ing the v ways to the spindle,, total ass crap! Stop and pay a professional! Oh right on can learn scrapping in a few weeks? WRONG!
This is so true! China can make exceptional products, we just don't pay them to, and then blame them for the poor quality we paid for!
You get what you pay for. Some people brag about all the money they did not spend then bitch about the quality the did not get.
One of the biggest problems China has is that they steal everything, especially from each other. So as soon as a high quality Chinese company makes a high quality tool, their neighbor steals it and copies it. I've actually seen copies of copies of copies, like Inception. The overall appearance and packaging of these copies looks *identical* to the originals, so when westerners search online, they of course buy the cheapest one, thinking they're all the same. Most confusing for westerners is that all Chinese companies sound the same, so they don't notice when two companies have names that differ by one letter. "Rolex" vs. "Folex" sorta thing. We all ultimately buy the cheapest of everything, which is why it always sucks. This will never change until China's culture changes, which is actually happening as we speak. That whole country is sick and tired of producing the world's crap.
Hi lkke your video on scraping but i really love your hatred for Chinese machines.I wish people stopped buying the crap.
наберите черновое шабрение
a) It is not my crossslide
b) you have a complicated way of saying that it is crap
Doesn't surprise me. Chinese cxxp
You get what you pay for, $1,500 for a Chinese machine and 40 hours labor to make it a close tolerance machine, Or $5,000 for a machine you use out of the box, you make the choice.
Like you scary to remove a lot of material.use hand power,no make a caress of that cast iron.go,go...
Available from whom? American importers? The main attractiveness of the Chinese products have always been the big profit margin for the unscruoulous merchants who try to profit from unwary customers. The Chinese are aware that those products are of low quality and sell them accordingly. For a higher price they produce quality tooling too, but you don't see it in many places because quality costs everywhere and in the mind of the typical customer, Chinese products must always be cheap.
replace ** with ss. That's bad.
The good thing is, you'll reliably never get quality, no matter how much you pay. I did make the mistake to buy an Optimum lathe several years ago. I'll never buy anything from them again. Nothing!
Buy a used industrial mill/lathe with five times the weight, recondition it and be happy.
I was buy optimum mb4 drilling/ milling machine, and that Z-Axis lean 0,15mm/250mm to y-direction, and 0,1mm/250mm to x-direction. I was reclamed optimum machines importer. And they tell at i must tell local seller my problems. I have hear any comment yet my local dealer. But that is true. I never go buy another optimum sheisse again
@@juhavuorinen3945 Yes, it is the seller who is responsible. Did it come with an inspection protocol? That would be a way to get you money back. Best get an consumer advocate or ask a consumer protection service.
@@MuellerNick i don't think, att i can get money back, becouse i have modified that cnc- milling machine. I think only way it is scraping machine true, but i don't have tools, and skill that operation. Tools i can made, but skill is another story
All that work for a piece of crap. Once scraped the cheap cast iron will wear away and quality will be back to crap. Should've bought a wore out American lathe and scraped that! I know it was a customers not yours.
That's the cheapest chinesium imagginable, and, it turns out... is quite cheap.
You should see the high quality chinese CNC machines that make plastic moulds. You get what you pay for, even for china.
Are some china made CNC's good quality?
Ah, those "pushy" Germans...just kidding!
LOL'd @ 3:32
This is not scraping, this is scratching.
Sorry.
And you are an expert at scraping?
your comment informed us you know nothing. Oil flaking is not scraping
"China quality" You've been inhaling chip fumes recently?, You got what you paid for and you invested the equivalent it would've cost you to get an expensive lathe in time, you actually put in more time on it than they would've have.
gushhnet You not be known much englich and talkin. belike moron in dogberrypatch.
Thank you Nick you patience and precision is inspirational.
Alan