Takisawa Lathe Rebuild Plan

[arsenix]

As a first scraping project I bought a Foster 8" straightedge. I did the machining and am now scraping the base of it. I have a Biax BL-10. I'd love some feedback. I did about 15 passes on it and it is looking I think pretty decent but the fine finishing isn't easy (not shocked!).

First pass is after I rough-scraped it (full stroke on the BL10). I dropped the stroke down as the spots got smaller. The last passes were set around 3mm for the last few passes. I can see that some of the high spots are "shinier" than the others and I presume these are the highest areas. Difficult to hit a single spot with the power scraper but maybe i just need to go slower and practice more. Would it be easier to switch to a hand scraper for the final passes? I may also just be going to light now. I notice a lot of my "chicken scratches" are on areas that are still showing high.

My plan is to scrape this in and then use it to spot the compound slides first. They don't have any particular "alignment" with the rest of the lather other than needing to be parallel with their base, so should be straightforward.

 

[Richard King]

Show us the tip of the blade and how you are sharpening it, what size blade width and length.. Is that a prism straight edge? How are you holding it to the wood cradle? Is it tight in the cradle?

 

[arsenix]

I have two blades. Both pretty worn down! Both "short", one has about 30mm radius the other about 140mm. I used the larger radius for the roughing. Both are pretty well used and I likely need to get at least one more blade. They came fairly sharp and I haven't resharpened them yet although I'm working on rigging up a diamond wheel rig (imminent). I may leave this where it is until I can properly sharpen the blades. I figured since these were already sharp I'd play around with them as is before buying more blades or sharpening them to different radii.

It is fairly tight in the wood cradle although not clamped. It can move maybe 1mm? Doesn't seem to move when I'm scraping.


Appreciate the tips!

 

[Bakafish]

They came fairly sharp and I haven't resharpened them yet although I'm working on rigging up a diamond wheel rig (imminent).

My experience is that, while old blades might seem sharp, those results imply that they are not nearly as sharp as you need and will create scratches and chatter. I bought some second hand blades and thought they were already sharpened and usable and got bad results. Only after really giving them a good hone did I start getting better control and clean scrapes. Lots of good ideas on blade sharpening here in this sub-forum.

 

[Richard King]

Those blade look like they are L side 90mm rad and R side 120mm. A simple trick to see if they are sharp enough is to see if you can shave a little off your thumb nail. We check fishing hooks that way up here in Minnesota. Then slide the edge along the side of the radius and the side of your finger nail and feel for any nicks in the blade.

Those pictures look like you started to try to get a bearing before cutting thru the machine marks. Pic one it is really noticeable. When your radius blade hits the machine marks you get chatter. Sets a height gage on the SE and use a .0001" indicator and check how deep your scraping. The minimum depth of high blue spot is .0002" and a max. of .001".

Your depth looks to low...You need to average .0004 to 5 tenths. Your blade looks dull. Those short blades narrow blades contribute to chatter. Use a wider blade 20 or 25 mm wide and 6" long blade ground at a 60 mm radius with a 5 neg degree rake on both sides of the blade. 8 degree if the iron is soft. I recommend sharpening brand new blades on a 1200 grit diamond lap for super sharp. Use a 260 or 600 to lap the smaller radius when roughing in the radius.

You need to grind a 60mm radius on the blades when your a rookie. Then the more points grind one to 40 mm radius. You need to buy one of my DVD's (also have USB sticks) as I show in there how to scrape 40 PPI. 3 sections on how to, 1) Hand scraping to 20 PPI and hand 1/2 moon flaking. 2) BIAX power scraping to 20 PPI and power 1/2 moon flaking 3) How to hand and power scrape 40 PPI. I sell them on eBay. If you want one, message me your regular email and I will email you. buy direct and I will give you a forum discount. I also sell the Connelly book and my training classes on eBay under "surface plates" or King Scraping

You can also see many of my students showing my techniques on You Tube for free - search "Richard King Scraping" NYC CNC and Stefan Gottswinter have some good ones.

You also need to move faster side to side on a diagonal line and have a gap between scrape marks the same width of the scrape mark, make sure you also separate the lines of scrape marks. If you scrape and don't get all the blue high spots, stand 90 degree's to the SE and scrape the ones you missed. Trying to get all of them on one side standing you will get chatter and dig holes. :-) "Practice Makes Perfect"

 

[arsenix]

Alright. Sounds like I need: 1) scraper diamond sharpener, 2) some long scraper blades, 3) Richard's video's I have everything in house for #1 I just need to put it together.

I think you are right that I didn't quite get through the machine marks when I rough scraped it. I still have low spots left over from the rough scraping as well, which I suspect means I went from "rough to fine" too quickly. I'll poke around on the surface plate a bit while I work on correcting my deficiencies.

Thanks for the advice folks!

 

[Richard King]

I tell the students in the classes. Shortening the stroke is like putting the brakes on when driving. You gradually slow down. Same with scraping you start with a long stoke and as you get more PPI you shorten 1 /8 turn at a time until your stroke is no less then 1/8" long. No need to shorten it less then that. A BL-10 longest stroke is 3/8" . Once you have a sharp blade off a lapper you will see how much easier it is. I see your in San Jose area. My friend D H Mayeron lives in Berkeley and he has a Glendo and would sharpen them for you, probably has a used 6" Blade. Email me and I will forward it to him. [email protected]

 

[wildo]

I bought some flex type blades from https://www.hudsonmachinerepair.com/shop
They have been good so far. It only looks like he has the 25-150 flex in stock, but you can email him.
You could also get the stiff style blades and thin them out.
There isn't much of a price difference vs Dapra, I mainly used him as he has an ebay store and it's easier shipping to canada.

 

[rmcphearson]

Any updates for us on the lathe?

 

[p3bhambama]

I bought some flex type blades from https://www.hudsonmachinerepair.com/shop
They have been good so far. It only looks like he has the 25-150 flex in stock, but you can email him.
You could also get the stiff style blades and thin them out.
There isn't much of a price difference vs Dapra, I mainly used him as he has an ebay store and it's easier shipping to canada.

I also bought a bunch of blades and handles from him. Good place.