Making a Boring Head Arbor for the Proxxon FF 230 Milling Machine using the Proxxon PD 250/e Lathe

[Music] welcome to adventures with a very small lathe the proxxon mill can't use most mill tooling most larger mills have a general purpose spindle taper which can accept boring heads chucks fly cutters and all kinds of tooling but the person only has a very short collet taper and a thread for the clamping nut cut directly into the spindle [Music] cheap boring heads have a large threaded hole in the top to accept an arbor which in turn fits into the spindle taper i could make an arbor with a straight shank to go into a collar but i'm concerned this would be too flexible instead i thought i could make an arbor that screws onto the thread on the outside of the spindle and i thought it would make a good entry for emma's spare room tool-making competition emma's competition always attracts some great videos and this year the quality of the entries is even higher check out the playlist at the top right now unlike most mill tooling a boring head doesn't need to be perfectly concentric as the boring bar is holding is always off center my first design looks like this and is quite large but once i checked the measurements i realized that the spindle thread was small enough to fit completely inside the thread that screws into the boring head and i came up with this second design this has the advantage of being less heavy but most importantly for the small mill it reduces the overall height substantially leaving more room between the boring head and the table the spindle head is 20 millimeters by 1.5 millimeter pitch the thread in the boring bar is less easy to measure and i wasn't able to find data online about standard boring other threads it looks close enough to a 1.5 millimeter pitch that it should fit over such a short length the diameter is less clear as the thread is only partially formed so the size may need some adjustment to fit i dug through my scrap bin for some material for the right size and found this bar of engineering still it's either en16t or en2040 and extremely tough i haven't made much from this bar before but i've usually been able to work it on the lathe it took about three minutes for the bandsaw to get through which should have warned me about the difficulty to come at least the bandsaw didn't throw its blade this time [Music] i started by facing one side the parts too large to fit inside the regular three jaw chuck jaws so i had to use the reverse jaws this means the part isn't quite as secure though it should be secure enough as it doesn't need to protrude very far the diameter and toughness of the material mean the cutting forces are pretty high and lathe struggles to produce enough torque to keep the spindle speed as fast as it should be i had to run the spindle a little faster than was ideal to make sure there was enough power to avoid stalling still one saw mark at the bottom to be removed i still manage a decent finish despite or perhaps because of the variable speed because the part will only fit inside the second step of the jaws my regular insert tool won't reach along the outer diameter without crushing the tool holder into the jaws instead i switched to a dcmt insert which is better at reaching into corners and i rotated the tool slightly to get more clearance i only needed a few passes to clean up the outside surface as this side of the part is going to be bored and threaded to fit onto the mill spindle this face of the part will be bored and threaded for the spindle which will tighten against the flat bottom of the threaded hole despite this i started by drilling a through hole as only the outer part of the hole diameter needs a solid bottom and the through hole makes boring easier later drilling big holes in tough material is one of the most difficult operations on a small lightweight lathe large holes should ideally be drilled at low rpm but as this lathe doesn't have a gearbox and uses an electronic speed control it has very low torque at low rpm this means there was no chance of making a twist or cut at low rpm so i needed to carefully calculate the highest rpm at high speed steel twist drill can deal with to make sure there was enough power after starting the hole with a center drill the first through hole was a six millimeter twist drill this cut fairly well and i was able to keep a pretty good feed rate without slowing the lathe down too much i stopped regularly to clear chips add cutting hole and check the temperature if the drill was getting too hot to touch i'd leave the machine off for a few minutes to allow it to cool this wouldn't be a problem at low rpm but at high rpms it's almost impossible to avoid rubbing which generates heat this part is large enough to build up quite a lot of heat as the drilling progressed so i tried to pay attention to how warm the part was as well the larger size made it took much longer to cool it's really easy to wear out the drill if it gets too warm and i don't yet have the skills to re-grind a twist drill this small the next drill was 10 millimeters in diameter and was quite a lot more difficult the drillers were removing material with a much smaller portion of his cutting edges is only cutting near the edge but this also means it needs more torque and the spindle was slowing down considerably it wasn't long before it jammed which maybe partly because the step up from the six millimeter drill was too small it looked like i damaged the outer part of the cutting edges so i switched to a different twist with a coating better suited to tougher steel clearing the burr rays when it jammed was pretty tricky but eventually i got past it and could make progress as the drill progressed the friction from rubbing on the flutes became more of a problem and eventually the second drill stopped cutting as well to get the hole finished i switched to a 10 millimeter solid carbide end mill sonic carbide can tolerate cutting at higher rpm and an emblem can cut reasonably well if there's already a reasonably sized pilot hole it doesn't self-center like a twist draw but that doesn't matter if this isn't the final hole size so inaccuracy and asymmetry aren't important i can fix them with boring later the flutes of the end mill don't clear material out of the hole very well as the shape for cutting so i had to clear them manually pretty often eventually i made it through because i'm a total masochist i then tried a brand new 12 millimeter high speed steel twist drill but that went nowhere pretty fast when i gave up it's just about possible to bore out a 10 millimeter hole with a ccmc inter boring bar but it takes the slenderest boring bar i have and has to be done with caution as this boring bar is quite flexible i set the length of the boring bar to be just a tiny bit over the depth of the hole i wanted so with each pass the tool holder would have to stop just short of the face this avoids any unnecessary flexibility the insert has to be bang on center height or the back of the boring bar will catch on the inside of the diameter i could only take 0.1 millimeter passes as deeper passes caused a lot of flexing and chatter strangely the boring bar seems to remove more material when moving back out of the hole despite being at the same depth as it was on the way in i assume this has something to do with the shape of the insert and the way the bar flexes under cutting load usually i switch to a larger boiling bar as soon as the hole is large enough for clearance but as i was making reasonably steady progress without any serious chatter i kept going by now there was clearly room for a larger bar so i switched up to a 10 millimeter boring bar and started taking 0.2 millimeter passes the flat bottom of the board hole is now well established and it's easy to tell from the sound when the insert is close to the face i switched up one more time to a 12 millimeter bar and started taking the heaviest cuts i could get away with the rest of the boring took quite a while so i'll take this opportunity to thank skillshare for sponsoring this video skillshare is an online membership community of creative people who enjoy learning people come together to share their skills and knowledge and expand their creative lives skillshare offers thousands of inspiring classes for curious people on creative topics like illustration design photography freelancing video and more if like me you've had to spend a lot of time at home recently now might be a great time to try and learn something completely new and the community has plenty of new things to choose from i've been doing a few more classes recently on the site expanding beyond the video storytelling film lighting color grading and video editing classes i did before i've recently been learning from the introduction to adobe after effects class by evan abrams and i'm learning fast the first 1 000 of my subscribers to click on the link in the description will get a two-month free trial of premium membership so you can explore your creativity back to tool making and the boring's nearly finished after the final pass i fed the tool across the back face to level it off this hole is going to be threaded so it needs a groove or gutter at the bottom to make sure the thread starts cleanly i don't have any internal grooving tools i could have ground one specially but this dcmt insert boring bar has about the right angles necessary to make a groove with a clean back face and a suitable ramp for the thread start the gutter catches the chips the tool makes as it forms so i had to stop and pull the tool clear to remove them i cut the thread starting at the bottom of the hole running the tool away from the chuck if this thread would have been extremely difficult to do threading inwards the risk of crashing would be very high and the chip clearance would be very difficult it's easier to see the gutter once i've colored the surface and to be threaded with a sharpie this color will also make it easier to check the pitch of the first scratch pass before setting up the lathe for threading it's a good idea to break the carriage down and give all the surfaces a good clean i used wd-40 to dissolve away the cutting oil residue and lightly stone the ground surfaces to catch any dings and bursts during single point threading you have the option to set the compound parallel to the surface of the thread to advance the tool in that direction this ensures that the threading tool only needs to cut on one face which can make it more stable and reduce collode on the tool this is especially valuable on a small light lathe like mine and i always use this technique as i'm threading away from the chuck with the lathe in reverse and the cutter on the far side of the hole i need to set up the compound to feed in the opposite direction from usual the angle of the compound needs to be set so that the leading edge of the single point tool is the one cutting material to make sure the cutting forces on the tool are correctly opposite to the backlash the tool post still needs to be square to the length of the bed to make sure the single point tool is at the correct angle the thread needs to have a pitch of 1.5 millimeters which requires the 22 lead screw gear and the 30 tooth change gear i tighten the compound give a little to make sure it was as rigid as possible and zeroed the compound scale the compound only needs to be adjusted over a short distance during single point threading i touched off to find the right starting position for the thread tool and zero the crossline the tool is now at the right position for the first pass but i needed to back it up two millimeters to be able to run it cleanly to the starting position in the gutter at the bottom of the hole i found the gutter by touching the tool holder against the bottom surface of the hole and then bringing it back one millimeter i fed the tool two millimeters forward again to return it to the right starting position and engage the lead screw feed it needs to stay engaged for the rest of the thread cutting or the alignment will be ruined for the first pass i set the lathe to its slowest speed and turned on the spindle in reverse direction always check the pitch of the scratch pass before continuing for the second pass i fed the compound in 1.5 millimeters the lathe can handle a deep second pass because only the very tip of the point is engaged with the material as the thread progresses the depth of each pass needs to be smaller as the engagement increases the threat took a lot of passes as most of the passes had to be really shallow because of the tough material i also had another problem the deeper the insert got the more it would vibrate and chatter this wasn't just a problem with rigidity this style of insert has symmetric relief angles appropriate relief is very important for internal threads where the curve of the material bends back towards the underside of the insert high quality threading tools are designed to have a tapered shim underneath the insert to adjust the relief angles to fit cleanly within the thread groove this tool has no room for such a shim so will inevitably cut badly on small radius internal threads in future i'll probably use a hand ground tool rather than insert tooling for this kind of thread so i can make sure the relief is correct as the thread nears completion signs of rubbing and chatter are obvious i used another dcmt boring bar to chamfer the opening of the thread and a curved needle file to smooth and deburr the crests the thread was the last of the operations on this side of the part so it was time to flip it around and start the other side there was a fair amount of material to remove from the second side so i thought i'd experiment with a new tool the external thread needs to be 10 millimeters deep and the tool also needs to reach a little further to completely clear and clean up the outer surface i chose this bryce carbide tool because it fits neatly inside the chuck jaws but still has plenty of strength and rigidity i had to grind and sharpen it with hand tools as i didn't have any grinding wheels for carbide yet i should have put more of a nose radius on the tool but that was far from the biggest mistake i made using this tool most experienced machinists will probably spot immediately what i'm doing wrong but i'll let things pan out before i explain so you can see what happened the sharp edge of the tool cut tough steel more easily than the insert i used before as inserts aren't nearly as sharp as hand ground carbide it had no problem even with deep cut this finished pass made a very stringy chip which i put down to a lack of chip breaker and i wasn't entirely wrong once the outside diameter was cleaned up i could re-measure the thread depth and make a witness mark to cut to at this stage the tool is still cutting fairly well but within a couple of passes it was starting to sound less healthy i added cutting all to see if that would help and it just kept getting worse the red sparks and blue chips should be a giveaway if it isn't obvious already i was running the lathe much too fast for this tool which happened because i forgot which belt ratio i had selected at the back and it was running three times faster than i thought eventually the tip of the tool was completely burned away and refused to cut anymore as i didn't have any practical way to regrind the tool i chalked the failure up to experience and went back to using the dtmt insert in order to reach in far enough i had to mount the tool at quite an angle coated inserts have a much higher cutting speeds than uncoated ground carbide and having recalculated the cutting speed i confirmed it was within the right range for this insert in hindsight this isn't a very good insert and eventually i changed to a better one off camera to finish the job the heavy material removal is now complete and to cut the thread gutter i need to move the part a little away from the chuck to get access with a grooving tool i used the shanks of two identical twist drills as improvised thin parallels to keep the part running true the first tool i tried for the gutter was this gtn 2 insert parting blade the insert is 2.2 millimeters wide which is a lot of engagement for this little lathe but i've used the tool before unfortunately i just couldn't get it to cut without stalling the lathe the second tool i tried was this much sharper hand ground high speed steel tool this started cutting no problem but very quickly started to chatter very badly the tool was extended very far from the tool post to make sure the holder cleared the jaws and this long extension made it way too flexible finally i tried a dcmt insert tool with a tool post rotated at an angle to ensure i could reach the right up to the face and still keep the tool as short as possible this was the best result so far but the insert still struggled to cut into the burnished steel switching to a better insert proved to be the final ingredient that allowed me to cut a reasonable gutter using the insert at this angle also gave me a chamfer on the thread start of about the right angle a quick check with a threading tool verifies that the gutter is deep enough once again i plan to thread away from the chuck but as the thread is external rather than internal the tool needs to be fed in the other direction so the compound needs to be flipped around to the other side of the bed the compound is still set at 30 degrees half the included angle of the thread the tool i use is a right hand internal threading tool which is ideal as it allows me to reach all the way around the far side of the part and cut on that side this is about the only way i can cut this thread away from the chuck on this small lathe the cross light doesn't have enough travel to move the tool poster to the other side of the part and the tool post isn't tall enough to mount the tool upside down this insert has symmetric relief angles just like the one i used for the first thread but as the thread flanks curve away as it's cutting an external thread the clearance isn't quite as much of a problem and there should be less rubbing i checked the tool region clearance before starting then touched off to locate the tool from here on the procedure is almost identical to the first thread i zeroed the cross slide then move the tool two millimeters away from the surface i then zero the compound set the depth of the first pass and engage the screw feed with the lathe on its slowest setting i run the lathe forward to move the tool to its starting position manually adjusting until it's right against the shoulder then reversing the chuck by hand until the backlash has been taken up i started the late spindle in reverse to make the first pass then check the scratch with a thread gauge the pitch checks out so the thread is good to go the next two passes went okay but then i noticed a loose screw on the tool post and tightened it this must have caused the tool to shift slightly altering the depth of cut which meant the cutting forces were too high stalling the lathe fortunately i could fix this by taking a couple of slightly lighter passes to clean up but already there are signs that this tough material is going to take a lot of passes to thread [Music] just as i was getting nicely into the rhythm of it i screwed up when my hand was passing the control panel i knocked the feed engagement knob and disengaged the thread feed as i was cutting a metric thread there's no straightforward way to get back exactly the same spindle position to re-engage and make sure the tool was still lined up with a thread often a mistake like this would mean the part was scrap but i put so much effort in that i was determined to realign it manually the process involved staring through a magnifying visor while i carefully adjusted the cross sliding compound it was almost impossible to see what was happening on camera and i stopped filming as it took way too long to be interesting one of the most important details of the process turned out to be making sure that all the backlash was taken up in the right direction while i was making the adjustments once i had the alignment back i plugged away at the thread for about half an hour taking dozens of shallow passes in the process i chipped all three points on the threading insert and i finished the thread with a new insert i had to check many times before i finally got a decent fit as the pitch was close but not quite right i deburred the crest with a lathe file then cleaned up the finish with a cratex stick the arbor was done and i couldn't wait to try it out on the mill the thread engages cleanly with the boring head and tightens it snugly against the shoulder it then threads onto the spindle as intended the bottom of the spindle tightens against the face at the bottom of the pole keeping the arbor steady the whole assembly spins just fine when everything is on center but the trick will be how it behaves when some of the weight is off center i visited new boring bar as a test and tried that out not bad so far though this is obviously a very heavy assembly for a small light milling machine let's see how it does when the weight is a lot more off-center clearly there's a lot more vibration and it seems unlikely i'll be able to do anything useful extended this far out a short while later my carbide grinding wheel arrived and i could properly grind the boring bar and use it for a project i needed to cut a 15.5 millimeter radius into the face of this brass shoe to replace the plunge lock on my hand router this is a good test as it involved interrupted cutting forces without having to extend the boring head too far off center it certainly worked well enough for this project but it was clear this mill isn't built to handle much lateral cutting force this was a satisfying project to get done as i've been planning it for ages and it opens up quite a few possibilities with the mill it also reinforces that i need a much more rigid mill than the proxon if i'm going to take on a lot of projects i highly recommend checking out emma's spare room machine shop and watch all the other entries in the tool making competition the standard of entries has gone up a lot since i won two years ago and i learned plenty from watching the entries myself the next video will be back to working on the chinese lathe [Music] i've already got quite a few improvements recorded and waiting for editing and plenty more underway [Music] recently i've been focused on precisely measuring some of the issues and working out the best way to fix them thanks for watching take care and i love you all you

Channel: Adventures with a Very Small Lathe

Views: 34,165

Rating: 4.8914728 out of 5

Keywords: Boring Head Arbor, Boring Head, Proxxon FF230, Proxxon PF230, Proxxon PD250/e, PD250/e, Proxxon milling machine, Proxxon lathe, Proxxon mini-mill, Proxxon mini-lathe, toolmaking, EN24T, 4340 steel, EN24T steel, home machine shop, mini lathe project, lathe project, lathe projects, milling machine project, mini-mill projects, Easy Lemon, proxxon ff230 micro mill, shop made tool, machining, make, maker, making, machining mistakes, machining errors, Kevin MacLeod

Id: DO2hJirGzQ4

Length: 20min 0sec (1200 seconds)

Published: Fri Jul 24 2020