TAIG lathe - dead center project. based almost entirely on Dean's instructions: Dean's Photographica.
I hope my experiments as a beginner might be amusing or helpful to those interested in getting started with hobby machining.
- Accurately chucking stock in steel indipendent 4 jaw chuck. I'm using a dial indicator to get it as accurate as I can.
- Grinding a Right Hand Facing tool out of a 1/4 inch square HSS tool blank
- Facing the front
- Turn diameter down to match blank collet diameter (less than .530")
- Set compound slide to make 15 degree cut (30 degree inclusive angle to fit TAIG headstock spindle taper)
- Center drill
- twist drill hole size: #7 3/8ths deep
- Thread 1/4-20 using plug tap to start and bottoming tap to cleanup and finish
- Flip the part, tighten in place with threaded rod, washers and nuts
- Turn 60 degree dead center
- Here's a small video which clearly shows the accuracy which can be obtained with a 4 jaw chuck:
No tool rest on the bench grinder, just freehanding and getting better at making nice single faces. I've practiced this before I got my DC motor, but had lots of difficulty on steel with 550RPM being the slowest speed. My geometries all seem to end up looking like knives. I'll have to look at more modern references.
Of course.. this is what it looks like when you don't have a single, uniform face accross the entire tool surface. You can clearly see it has a minimum of 3 faces now.. no worries, I was just tweaking the overall angles and this will happen. I am finding it easier to keep track of which face is the one I just did, so I can try to correct it. I haven't produced a tip yet.. I'm kind of using knife bevel (2x72 grinder) technique of working my way up to a line.. in this case it's inverted and I'm working my way slowly to the point.
getting a little better
turns nicely, had to really lower the RPMs and feed inwards in the smallest increments I could manage. It was actually the most annoying and difficult part of making a good cut. The part snagged a few times and actually stalled the little belt.. time for a dial indicator to truly gauge how my hand movements are translating to proper feed. I think the rack and pinion setup of the carriage is way too fast for me right now. I don't feel like I can make accurate cut measurement in its current form. I'm going to have to look into gearing it 1:10 or something. (projects just keep sprouting more projects.. eheh)
some chips..I like it when it curls tightly, which required fairly fast turning to achieve consistently. I'd like a little more granular control. On a bigger machine, it feels much more "natural" to me in terms of "rythm". Maybe I'll get used to it.
- this little video below might be a better indicator of how well the tool cuts. I practiced a few times to get the plunge just right. I should also mention when you see tool moving forward towards the part, you're in full macro zoom. To me, that was barely perceptible. And I would say I turned the carriage wheel about 1/100th of a turn. Even just 1 past would cause chatter and even stall the belt. I managed to get it right about 50% of the time. Which is why I think I'll need some way to really tell how much the tool moved with respect to the part.
this is the face after the last cut in the video. I still have to put a bigger radius on the tool tip to really get rid of those groovy vinyl record type lines. Which I normally find so pleasing.. on records that is.
- ERROR!After going back to my South Bend "How to Run a Lathe" book, to look at geometries. I realise I basically made a LH facing tool, with the cutting edge on the wrong side.. nice. Always fun to discover new and interesting ways to mess things up. Easy enough to fix. I basically repeated an earlier error from many months ago. Because I just looked at how I had ground another bit and replicated it. I mean, it'll still cut, and I'll experiment with it. But for clarity, Right now, I'd prefer sticking to well documented methods.
Of course.. the more I look into it, the more I'm seeing it's not entirely clear cut.. I'm wrong to call it a "roughing tool" as a roughing tool will usually have the side with more meat behind the cutting edge. I did see some RH "finishing" tools which looked like what I tried to do. In this earlier photo, I was trying to show the angles of clearance near the chuck. So I could cut from tailstock to headstock (right to left) and also use it to do a facing cut on the front and the bevel...I think that's my issue. I'm trying to do too many things with just one tool..
- I had seen a great vid by OxToolCo on youtube, and found another very well done reference here:Steve's Workshop
So I was a little more methodical this time. I did my homework.
That discoloration kind of worried me. But most of the edge was straw or gold.. which would be where I'd normally try to temper a cutting blade. The blues and purples are bad. Those become softer, not optimal for edge holding characteristics.
I didn't hone it this time.. I went direct from grinder to cutting test. I saw a great suggestion from the Sherline Lathe tool bit grinding page. About small machines using only the point to do small but clean cuts. That a lot of the reference material generally looks at optimized production on much larger machines, where more of the cutting edge is engaged in the cut. I tried to keep that in mind. Noticed last time, the diamond hone made it feel rougher. Not sharper. This one feels SHARP.
Incorporating a chip breaker would be nice. I'd have to see if I have anything small enough on the dremel to cut a nice groove parallel to the cutting edge. You know. Right over there by that nice flat part near the egde. The flat that's totally not supposed to be there.
- I like this swarf. But I don't trust it... I've been stupid and tugged at swarf in the past which didn't seem attached. It sliced deep into two fingers simultaneously amid a concerto of swears that haunt me to this day.
Nice! A little deburring would be required. But I'm going to move into cutting the actual forms I need for this project. I can barely feel those lines and I could finish with a nice sandpaper polish.
I cut the diameter for a 1/16th long section, to match the TAIG collet you see on the right. I left a little extra meat there, for when I cut the taper, I imagine I'll dig into that face a little and it leaves me some room to do a final cut.
This is the basic setup for drilling with the tailstock. It worked really nicely for center-drilling, twist drilling (#7 twist drill for 1/4-20 thread) and finally threading. Although I had more control putting the Tap in a regular manual holder while turning the chuck by hand. I used the Tap in the tailstock to get it started, but I didn't have enough "feel" on the tap with both ends in the lathe. So I switched to a manual tap holder instead of relying on the tailstock. Which is really the only option if you don't want to remove the part from the chuck.
this shows the threads.. they look like crap in this closeup. I have to find a way to clean that without an air hose.. (now didn't I see a video about making a DIY ultrasonic cleaner? add it to the list :)
Turned the outer diameter to size along the length I'll be using. The finish is quite nice. Better than the stock blank collet which I'm holding in my hand for comparison. You can see the 15 deg (30 inclusive) angle which is currently missing (also you'd have to flip the part I am holding to match how its currently mounted in the chuck). That is the part which will get pulled into the corresponding taper of the headstock for the final operation.
Swarf! pesky stuff gets everywhere..
Setup the cross-slide attachment for cutting the taper
closeup of the finished taper which goes into the headstock. I thought I had some 1/4-20 threaded rod.. but it turns out it's left hand for the "leadscrew" conversion project :) So it looks like I'll have to pick some up this week to show you the last step. I did remove it from the chuck and check that it fit nicely in the headstock and it does! Which is nice, because I had to "eyeball" the angle using the collet blank as a guide. Very happy with the finish.
I'm also getting more used to the little knobs and finding ways of feeding consistently. I really haven't been using the markings at all though.. I prefer keeping my focus on the cutting. The sound, the feel, the speed.
Looks like I have to order some stuff, might try to get an inexpensive plunge type dial indicator just to mount and monitor my true movement with the infeed dials. Right now I couldn't really tell you how much I'm taking off per pass. I stop and measure often. Moreso when getting close to the final pass.
a little blue tac to hold them while I snap this. The fit in the headstock was nice. The collet blank on the right looks a tiny bit smaller. But it didn't seem to adversely affect the fit. Once I can tighten it in place, I can look at the runout on the part which will now be sticking out. As well as some prussian blue to see if the bearing marks (points of contact) are nice and uniform.
- I picked up some threaded rod and installed it to check the runout. It's now clear that my angle on the taper is just a little off, so it isn't properly centering in the headstock taper. I should be receiving my simple protractor tomorrow. So I'll show how much it's off, and how I go about fixing it.
Started over with a new part. This time I followed the recipe perfectly. I used the protractor to set the angle as best I could. I also faced it, turned the outer diameter, the taper, the little shoulder at the end of the taper and THEN I set the tailstock center. Touched the part and saw it was also slightly off. I blued the end, adjusted the tailstock and the dot in the blue was perfectly centered. It didn't shift at all while turning.
- You can see in the short video below. I then cut the part, flipped it around and installed it in the headstock. The final result is quite nice, same +/- 0.0001" I was able to get with the part in the 4 jaw chuck. Now I just need to cut the final 60 degree center and this part is done.
- TODO: cut final 60 degree center point. Re-use previous part with incorrect taper, cut and through drilled to act as centering nut on back of headstock where the draw bar gets tightenned. Right now, depending on how carefully I tighten, I am not always getting a nice perfect alignment.
Which leads me to conclude, my angle may still be off. I am probably going to make another part tomorrow. This time not using my protractor to set 15 degree taper. But rather, use the protractor to transfer the angle from the stock collet to to the taper I want to cut. Would you believe it. The stock collet doesn't measure out to 15 degrees on my cheap little protractor.. but 14 degrees. Considering the stock collet fits perfectly into the headstock, I'd like to see which one of the two gives me a nicer fit.
I also want to know if I can trust this protractor or not.
index of projects:
- Mountaineering Crampons
- TAIG Riser Block
- TAIG DC motor mod
- TAIG Dead Center
- 2x72 Belt Grinder
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