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Scraper Build

Turning the Handle

Turning the handle wasn't as big a deal as expected because it was already round but just too big for what I wanted. The piece of walnut was also about twice as long as needed so I figured out empirically how long I would need to part it off and turn what was needed from the tail stock back, then cut it off accordingly. Nice because it left a piece for another smaller Pommel-type handle in the future.

Chucked it up, put a live center in the tail stock and aligned to an existing center dimple on the end of the piece.  It spun pretty true, so off I went making A LOT of wood chips and dust!  I used a standard carbide insert tool and engaged the half nuts to let it get down to the major diameter I wanted.  I could take about 20thou cuts (radially) without much effort at probably ~800 rpm.  I have no idea if this was the right speed but the finishes were decent and without chatter or gouging.  Later I moved to a high speed Radius bit for some cleanup.

Once it got down to the rough large diameter I started making shorter passes and feeding in gradually to get the rough shape you see below.  Then proceeded to turn the ferrule portion down to about Ø.875" as I wanted to put a brass threaded insert for the shaft in the end and still fit the piece of Ø 1.125" RB brass for the ferrule.  Here are a couple of shots while on the Mini...it Can be Done!


From this point I moved to files and sand paper to finalize the shape and get down to first blush on finishing.  Next was to part it off and work on the radius for the palm end.  I knew the ferrule section was straight and long enough to hold in the chuck but would need to be careful because it would be free floating without a steady rest in my tool belt.  Worked out OK and was able to get the desired result even with the long, unsupported throw.  Here is an end shot in the lathe.

https://sites.google.com/site/pjsminilathe/my-projects/scraping-tool/scraper-build/Handle3_090415_web.jpg

Once I got the shape and reasonable start to the finishing, it was time to figure out how to end drill and tap the wood for the threaded brass insert I was going to make. It was going to be ½ x 13 outside with a 5/16 x 18 inside and about 1” long. Unfortunately there are no pictures of this because I was caught up in the moment of how to do it. The handle was too long to chuck up and use a 27/64 bit in the tail stock and the same applied to my drill press…so I had to figure a way to hold it in the vice straight up and drill by hand as straight as possible.  Also because it was necessary to insert the shaft well into the handle, it needed to be drilled to 2 sizes and depths. I started with a ¼” bit and drilled to full depth and a skosh. Then moved up to a 3/8” bit and followed down to about 1-1/8” depth to give room, just in case and allow for final finish work. Last was the 27/64 drill to the same depth. I had tapped wood before on my drill press table so very carefully started taping. The finished thread (½ x 13) on the inside was a bit rough but worked out in the end by running a bolt in and out several times until it felt right. On to making the insert.

Single Point Threading Brass


To do this it was necessary to set up my gears first and check that I was getting ½ x 13 as this would be my first SPT in a Long Time.  The mini calls for 45, 65, 60 & 30 tooth gears in the ABCD positions, respectively and to use the #1 on the thread dial when starting.  I set up all the gears and checked the gear clearance with small strips of paper to create a nice accordion effect when run between the gears, spinning the chuck manually.  Once satisfied I turned on the mini to the lowest speed to listen and watch them spin for run out and noise.  All seemed real good.  Next was to set up the compound to 29.5º and check with the fish tail for squareness to the piece of AL RB I was going to use as a Guinea Pig and practice a few rounds before starting on a piece of brass.  I used my threading insert tool with a .0156 (1/64) radius insert.  Off I went making a scratch cut and checking with the thread gauge…all looked good.  It took about 8 passes to ease into the rhythm of starting & stopping the feed, backing out, moving back and catching the “1” on the thread dial. Got to depth and checked it with a nut and was a bit tight so, took another shallow pass and a skim pass…overall not bad for a first thread in a hundred years.  Parted it off and did it twice more to learn how to sneak up on the final size/depth to get a no-Wobble nut…somewhere between a 2A & 3A thread class, I think.  OK then, on to the brass.

I chucked up a piece of Ø.50 RB Brass, hit it lightly with sand paper to brighten it a bit and proceeded to cut the relief at the end of the thread.  The fish tail gives you the numbers for the depth of thread; I used a .060 parting tool to go to that depth with the dial on the compound.  Actually I took about a pass and a half to get about .080-.085 wide relief to give a good parting spot with some room for clean up.  Then setup the threading tool and off I went.  Glad to have practiced on AL as it is a bit gummier to thread than the brass.  Only used a tad of threading fluid along the way and they came out Real nice, and the nut felt true and snuggish, so it would get a good bite into the wood.  Next was to drill and tap the 5/16 x 18 in the center.  I did this with a drill and tap in the mini to control the concentricity, and then parted it off.  I cut the slot with a hack saw in the vice soft jaws.  Here is what it looked like finished but not thoroughly cleaned.


Making the Ferrule

The ferrule was pretty straightforward machining.  Although really wanting to try Tony’s forming trick, I stuck with the traditional turning and boring to a close fit on the wood handle and shaft.  Started with a piece of Ø 1.125” RB brass and turned it down to a few thou over the size of the lip diameter I left remaining on the handle.  Drilled a ¼” hole to the desired depth, then used a 7/16 end mill, then a ½” end mill (largest I have).  Next was Boring in many senses.  Loaded a boring bar in the holder and proceeded to walk the ½” out to .875 creeping up on it and trying the handle over and over again until I got it where I wanted it.  It has about .080 walls (substantial I know) so I parted it off with about that much on the face end.  Then flipped it around and faced off the flat end to get the finished size.  Here are the rough pieces.

https://sites.google.com/site/pjsminilathe/my-projects/scraping-tool/scraper-build/Pieces2_090515_web.jpg

Making the Brass Coupler

Again this was pretty straightforward machine work using Hex Brass.  It needed to be long enough to get a good depth for the shaft thread (5/16-18) and enough depth for the insert tools to be stable and have a close tolerance, sliding fit.  Chucked up the hex stock and faced it off then bored the tap hole size (F drill) for the shaft to depth plus a skosh to compensate for the 135º drill point and get a good tap all the way down.  Put the tap in the tail stock and tapped it, then refaced and rounded the corners a bit to get a good jam with the nut I was going to make. Then it was slightly deburred with a countersink. Parted it off to the length I had determined and flipped it around in the chuck.  Faced it off and drilled a 1/4:” hole to the depth I wanted for the insert tools and worked my way up slowly to an “N” Bit (.0302).  I mic’d the O1 tool steel and found it was about .0012 over size then decided to use a 5/16” end mill bring it to size.  Still a bit tight, so I decided to chance using a 5/16 (.3125) bit because I don’t have any reamers but do have multiple 5/16 bits.  Typically drills have a tolerance of up to about .005 diametrically. After measuring them all, I chose the one closest to .3125 to drill it.  Basically I just spun the chuck at about 800 rpm and ran it in an out a few times.  It all worked out perfectly because after a bit of polish of the O1 and the inside of the hex it made a “Popping” sound when I pulled it out!  Nice…Whooohoo!  I lightly faced off that end again and counter sunk slightly to debur, then rounded the corners a bit to finish it off.  The nut was again pretty straight forward.  I wanted a thin jam nut, and drilled the hex with an “F” drill again and tapped it.  Then deburred and rounded the corners and parted it off a bit thicker after using the tool bit and file to create the rounded corners on the opposite face.  There was enough thickness to still be able to chuck it up and face down to the thickness I wanted then lightly touched up the rounded corners. 

There, That’s Done…except now it was necessary to drill and tap a 10-32 hole dead center on a flat so I could lock the insert tools in place and keep them from rotating.  I messed up a bit because the drill walked a bit in the drill press…guess I didn’t center punch deep enough or didn’t line it up carefully enough, but it all worked out in the end…But the Shadow Knows it’s off!  @¿@  Here are a couple of pictures.  I may make a knurled thumb screw in the future but want to try it out for a while with the SHCS…takes very little force (finger tight) to hold the tool in place, real tight.



Making and threading the CRS Shaft – and then some

The shaft is a piece of 3/8” CRS about 14” long.  It wasn’t a super clean piece but touched it up with a few grits of emery in the mini.  It was too long to fit on my current 10” bed so the sanding had to be done in steps by turning it around in the chuck and matching up the sanding as best I could. 

Originally the plan was to use a 5/16-18 die to cut the threads but have always found cutting threads with a die on CRS to be a pain and generally have poor results.  Since single pointing the brass insert I figured OK let’s try it on the CRS.  This is where the learning curve (Curb) began! 

(The tale of 3 or 4 gear setups and backlash)

First the gears got set up as I thought they should be based on the chart, which is 40, 65, /, 40 (ABCD respectively).  The / indicates (supposedly) that it doesn’t care which gear is in that position.  I actually don’t remember what gears I tried (and tried a bunch) in that position, because none of them worked!  Each gear produced some pitch other than 18TPI.  I must have gone through 2 feet of 5/16” AL RB, 1.5” at a time while trying to finger it out.  Finally, instead of cutting metal, I set up my dial gauge on the carriage stop and hand turned the chuck while counting revs to see what the pitch was.  Got everything between 16 and 24, but no 18…and got a few odd balls in the middle like; 21 and a skosh!!  The gears and banjo on the mini seemed pretty straight forward for setup, I thought. 

The A gear bolts directly to the drive gear,  B&C on the banjo use a steel bushing between them but could be large on the inside or outside and still engage with D…However that was my mistake.  The D gear attaches to the end of the lead screw and had a keyed spacer bushing between the gear and the shoulder of the lead screw.  The thing that kept niggling in the back of my mind was the chart on the gear cover shows a 3 and 4 gear setup…so why would the / not matter??  Turns out, (when the light bulb finally blew) that the spacer bushing goes on the inside (between the gear and shoulder) when using a 4 gear setup and on the outside of the gear when using a 3 gear setup.  This would mean that the C gear wouldn’t touch anything but is required to be able to secure B&C to the banjo!!!  Hilariously about a month after this discovery Mr. Pete on YT did a series on changing gears on an old Craftsman Atlas; he brought to our attention, that nowhere in the books does it talk about switching the placement of the keyed spacer for this purpose…Whoohoo, a month or so later and too many hours of head banging along the path I was finally confirmed Non-Nincompoopus!  Well almost…~¿@

Again after finally getting the pitch right I found some other issues with single point threading on the mini that will hopefully help other novices.  Luckily I had a couple of 3’ sticks of 5/16 AL RB to practice with to finger it all out.  First was double threading on about the 2nd or 3rd pass, even if I very carefully engaged the half nuts at exactly the 1 or 5 mark on the thread dial…tried both  marks several times…same thing!  This turned out to be the backlash in the lead screw and included a major cleaning, honing and adjustment of the half nut assembly which I hadn’t done since purchasing the machine.  The lead screw backlash adjustment is a bit futzy and will probably mod this feature on my new 14” bed.  Basically you have to loosen (but still snug) the 4 bolts on the bushings, with the half nuts engaged and the carriage roughly in the middle of the bed and free to move, then press them toward their shoulders and tighten a bit at a time until you get a free spinning lead screw but minimal backlash.  It’s better if you disengage the banjo first and that lets you spin the gear on the lead screw by hand for feel.  Once that’s all done you will get almost perfect tracking every pass.  On fine pitch threads this will be critical in my opinion.

The second issue that arose while practicing on AL was using the carbide insert tool.  At some point I got sharp threads but the root flat was too big.  I got out the Machinery’s Handbook and checked.  Sure enough the root flat on an 18TPI thread should be ~.0108 and the radius tip of the insert is .0156 (1/64).  So I ground a new Hi Speed bit to a good sharp tip and touched it up a bit with a DMT extra fine diamond hone.  Now we were cooking with Gas!

(Finally – The Shaft)

After all the hiccups, head banging, practice and then some, I started the threading on the CRS Shaft… WhooHoo!  It all went pretty swimmingly, cutting the first threads on the coupling end.  Note the relief is about .080 wide, maybe a bit too much but didn’t want to accidentally ding the 3/8 part of the shaft during repeated  feed passes.  Also a Note for novices about the fish tail and the numbers on the pointed end, indicate the depth of thread for several pitches.  In the case of 18TPI it is .072.  This is handy for cutting your relief depth, as you can touch off the material and just use the cross slide dial to go into the material to that depth.  It also gives a visual indication as you approach proper thread depth; using the compound (as you are supposed to) is not a reliable dial value because of the compound angle being 29.5º.  It becomes a trig function with respect to the dial.

The other end worked out OK too but involved a bit more turning, first because of the Ø.250 straight section I wanted to embed further in the handle to take out any probability of wobble in the handle and threads.  Then turn the threaded section to Ø.3125. When it was all done I decided to blue it because there were some blemishes left in the shank and it looks cool to me.  Making the shaft and threading it on the mini was a bit of a learning curve but it came out pretty well and quite happy with the CRS threads in the end.  Now I won’t hesitate to make threads on the mini and may write up some more (in Making Chips heading) after trying a few more types!  Here are a couple of pictures of the completed shaft.


Making the Interchangeable Tips

The concept for these really fits the multiplicity of the tool and that they are relatively easy to make, repair, and sharpen.  After sitting for a while pondering the various carbide pieces that I got from my friend Jimmy, I decided on a wide and narrow version for push scraping.  For the third tip it seemed possible to  make a version that would use the TCMT inserts I use that could be rotated as necessary and maybe fulfill the need to get into corners of dovetails because it’s 60º.  I also wanted a pull scraper of some kind.

Starting with the wide piece first I chose the 5/16 O1 tool steel for rigidity and toughness. The piece was ~3.25 long, as that felt about the right length overall with the handle and coupling, so I cut off several pieces for what was in mind thus far.  Next was to figure out how to create a good flat for the set screw and cleanly create a shoe section for brazing on the carbide.  Turned out the Mini did the Milling also!!  First I faced off both ends of all the shafts, then inserted them into the coupling and marked them through the set screw hole so they would align nicely with the 10-32 set screw.  Next I chucked up a ¼” end mill in the mini and mounted the O1 rod in the tool holder fairly close to the tool post and adjusted it until I found center of the end mill.  Sparked up the mini and proceeded slowly to feed the stock into the mill with compound, until it reached a good depth for the set screw to hold it well.  Deburred it and checked in the coupler and Shazaam…worked great.  Did the other pieces since the mini was set up for that…There, Done with that!  This turned out to be a real boon to the next step of creating the various shoe profiles on the other ends.  What it gives is an angular reference locking point in the holder.  In other words one of the 4 screws on the holder can “Locate” or orient the piece in the holder with respect to the chuck with an end mill in it.

Creating the shoe this way worked real well and gave surprising finishes. For the large and small tips the shoe is just a flat mill with a sharp corner.  One is a bit deeper than the other but only because the carbide pieces are slightly different thicknesses and depths for brazing.  A couple of pictures are probably worth a thousand words so here they are.  Note the holder is upside down in the pictures; this should give a good idea how they were milled in the mini.

I had picked up some pre-fluxed Harris Stay-Silv 56 a while back for something else and used a little Oxy-Map torch to braze them. Here are a few pictures of the silver brazing and clean up.




Here are some early shots of the initial three tips, but the third one (pull type) didn’t turn out that way because of issues with using a screw in that fashion.









Basically the pull scraper was originally milled off flat at 45º to allow for the 7º relief and the angle I would be pulling at with the handle, but there was no way to put a 3mm screw into it without breaking through and keep it enough below the shank to be effective. Originally I thought of trying to grind a shoulder (with a Dremel)  into the O1 to capture the triangle a bit, but have temporarily abandoned the idea for maybe larger inserts and a different profile on the shaft to support it and a screw. What I came up with used one of the pieces from Jimmy and only needed a little more creative milling on the shaft to support the angles for pull scraping and the carbide. However it inverted the flat for the set screw…but no worries, the scraper is round and the set screw can be on the bottom when in use!! ~¿@  Here is a final shot of the three finished pieces.

https://sites.google.com/site/pjsminilathe/my-projects/scraping-tool/scraper-build/Scraper_Pieces_Finished1d_092615_web.jpg
https://sites.google.com/site/pjsminilathe/my-projects/scraping-tool/scraper-build/Scraper_Pieces_Finished1c_092615_web.jpg

As for sharpening, honing and relief angles this is still a bit of a WIP. These don’t need to be “Scary Sharp” primarily because the carbide is so brittle and will chip but they do need to have a straight edge and a decent relief angle with respect to how the tool is held. I tried to touch them up with my DMT tools but it’s difficult to maintain a straight edge and most of my DMT stuff is Fine or above. I picked up a 6” 120 grit diamond wheel on EBay for a good price and mounted in the newly refurbished free grinder but it tends to cut an arc and can’t be used on the flat sides although it works well. I have an inexpensive baby diamond cup wheel but it has way too much run out for my taste. The same guy (JadeCarver) that had the grinding wheel has 6” steel backed diamond lapping plates very inexpensive ($15 ea.) so I bought a 360 and 600 grit, but need to make something so I can spin them at proper speed and give me what I need to put a nice edge on these. I’m also considering some 1x30 zirconium or silicon carbide belts for the baby sander which should do a decent job. They are available from TrueGrit for decent prices. They even have diamond micron belts but more pricey! Like I said this is still a WIP process but for now they scrape the piece of 1” 100 XF steel plate I have pretty well. Also tried them on various pieces of material around the shop and do even better with the much softer unknowns, probably like the new 14” bed has.

Finishing

Most of the finishing you see in the following pictures was done after all the components were built. The wood handle took the most time because I had originally started with hand rubbing 100% Tung oil thinking this hard wood would go quickly, but the drying times were horrendous even with thin coats. In the end I picked up some Minwax Tung oil which has some esters in it which helps the curing process. What you see is about eleventy two coats, hand rubbed and sanded between coats with finer and finer sandpaper to a micro polishing pad then two more just hand rubbed in. The fits on the brass insert screw are so good I don’t need to glue it in, at this point. Even the ferule fits very snuggly, especially with the shaft in and the narrow tolerance for the through hole…although it may get glued in the future.  I used semi-chrome on the brass pieces as a final. The rest of the metal was just sanded and or polished up to micro polishing pads on some. The bluing on the shaft was just done with Birchwood cold blue which hid the blemishes pretty well and should protect the CRS from corrosion.

https://sites.google.com/site/pjsminilathe/my-projects/scraping-tool/scraper-build/Scraper_Pieces_Finished1b_092615_web.jpg
https://sites.google.com/site/pjsminilathe/my-projects/scraping-tool/scraper-build/Scraper_Pieces_Finished1_092615_web.jpg

https://sites.google.com/site/pjsminilathe/my-projects/scraping-tool/scraper-build/Scraper_Pieces_Finished1e_092615_web.jpg
https://sites.google.com/site/pjsminilathe/my-projects/scraping-tool/scraper-build/Scraper_Pieces_Finished1c_092615_web.jpg

Epilogue

It’s been quite a journey getting to this point. The physical time to build this is hard to estimate but a few hours a day for a few weeks is about what it took. Like most of the things I do this was done on the fly with no drawings however I may create one as a reference for the future tips, shanks and handles.

I hope the write up and the idea of this kind of tool helps others and particularly novices like me. It covers many processes and techniques and was a great learning along the way. Like I said earlier, scraping is a Zen space for me like sharpening and honing, and when it’s done there is a beauty and simplicity to it and you get to use it!

Now it’s time to put it to use. This bench plate is something I’ve wanted for a while too.  I got this 7.25” round by 1” thick drop from my brother, who got it from a friend who works at a CNC plasma or laser cutting shop.  Pretty sure it is 100XF steel based on what he told me, because it hard as rocks (hi Si content) and had to start with 36 grit sanding discs (2) on my angle grinder just to get the fine rust and slag off of it. Currently, I’m up to about 320 grit, and all the visible hollows gone on one side and about 220 on the other. Sure would be great to have access to a surface grinder!! Once the other side is up to that level I will put it on the granite for a measure and possibly check it with the Prussian Blue to get started…Scraping!

https://sites.google.com/site/pjsminilathe/my-projects/scraping-tool/scraper-build/Bench_Plate_80G_web.jpg

Preliminary work on the bench plate.  Left is up to ~100 Grit, Right is up to 320 Grit.

Then on to the new 14” mini bed and cross slide which is now within a thou or so of square and true as it can get, in 3 axis and a lot of hand-work. 

It’s always a journey, making chips or dust (and now sawdust) with the mini but a fun one in all respects!   Till Then, ~PJ