Small Milling Machine Improvements - PM-728VT

a very reasonable question would be how do you sit comfortably with that horseshoe up your ass and all I can say is a combination of cheeseburgers and you get used to it hello Internet my name is Quinn and this is bloody hacks as regular viewers know I recently upgraded my milling machine to the PM 728 and it's a fantastic machine as I said in the video where I reviewed it it's uh it's very very solid in all the ways that matter you know the waves are really nice the lead screws are awesome spindle bearings drive system all First Rate really really nice machine where it falls down a little bit is all the little quality of life things the little niggling details that that nag at you every time you use the machine and those are the things I'm going to take care of in this video it's kind of a collage of all the little modifications and improvements that I've been making over the few months that I've been using that machine so I hope you'll find something interesting here whether you're a 728 owner or an owner of any other small milling machine all right let's go I started with the biggest no-brainer of small milling machines and that's to install a priest tools power headlifter Greg makes these kits for all manner of small milling machines not just Precision Matthews he's got kits for Grizzly and lots of other machines so chances are he's got one for you and let me tell you once you've lived with a power headlifter you will never go back to cranking that thing up and down if you've got an email there are companies that make knee Mill Motors as well once again once you've lived with it you will never go back especially on a machine like the EPM 728 where the head is actually quite heavy so the crank you can see there is quite big and the gearing is low to give you some mechanical advantage but that means you do a lot of cranking and your shoulder is gonna get sore I'm zipping through this because I've already done an entire video on installing one of these kits so if you want the details here I'll link to that video below sometimes it's the little things this armored cable drags on the edge of the aluminum shield for the dro and makes a rattling noise when the head moves up and down this is an easy fix courtesy of gaffer tape not duct tape gaffer tape the good stuff or the consumer version of it Gorilla Tape while we're talking quick wins there's these two random threaded holes in the front of the casting no doubt they are there for some other machine that uses this same base casting these castings are made by foundries that then sell them to the Chinese machine tool companies that then use them for various machine tools that they sell and so they often have random holes in them like this that are used for some other purpose that does not apply to this machine they were all full of paint but I was able to determine what thread they actually were and Chase the threads and then I just put some little set screws in there to keep chips and oil from accumulating in there and piling up inside the base forever that's all fine and good but let's get to the real reason we're here when I did a review of this machine after first receiving it you might recall that I did some heavy test cuts to see what this machine was capable of and during those test Cuts I noticed what seemed like a pretty substantial issue and that's that the quill apparently pulled itself down three thousandths during that cut I had set that depth of cut to 50 thousandths with the quill and as you can see by the end of the cut it was showing 53 thousands it seems as though the quill lock is insufficient or something else is wrong such that the cutter is actually being pulled down into the work during the cut now after several months of living with this machine I've determined that that's not actually what's happening that much of a cutter movement would be showing up as taper in the parts and this machine's cutting very parallel so it isn't actually moving the cutter there's something else wrong well then one day I noticed this give it a little Yank on the mounting bracket here and look how much Flex there is in that you can easily pull it out of whack by a good twenty thousands and after you pull on it it doesn't go back to where it was it goes back to some random place that's two or three thousandths off from where it was so this appears to be the actual problem when the quill and the head of the machine load up under cutting forces that bracket flexes and doesn't go back to where it was when the cut is done so this chintzy little sheet metal bracket I think is the actual problem for this apparent three thousandths of movement on the quiltyro the cutter is not actually moving just the dro scale is moving relative to the quill this seems like really good news because hey we can fix a chintzy bracket now let's not stop there though because if you watched my review of this machine then you may recall that there was a number of issues with this quilt the arrow the other big one was viewing angle on the LCD is quite poor you can't read the numbers very well unless you're crouched down and looking directly at it and this thing has an auto shutoff as many of them do but the timer on it is very very short it actually Auto shuts off during a long cut which is really annoying in an optimistic effort to solve all of these problems all at once I spent some quality time on AliExpress and decided to see if I could find a quill Dro that would fit in a space occupied by the current one but did not have all of these niggling issues this is the one that I landed on it's by shahe or Shea shahe I'm not sure how to pronounce that but I'll link to this one below this is one of the more common brands of these digital calipers and scales so these are not hard to find I chose this one primarily because it seemed like it had the features that I wanted in the description but more importantly the description on AliExpress had mechanical drawings in it so I was confident it was going to fit that's very difficult information to get for something like this when you're buying it on AliExpress getting the exact dimensions is often difficult but this one had the drawings so I was confident it was going to work quick test here and it does seem to work and importantly the viewing angle on the LCD is excellent as you can see all different vertical angles it still seems to be very readable that's a really good sign we're off to a good start now I'll see about mounting this thing inside the head not sure exactly what that's going to require but there's only one way to find out fortunately this thing is quite easy to get out of there it's just held in place on the bottom by those cap screws that attach it to the chinsy bracket and then there's a single cap screw in the casting that attaches the body of the dro to the Head let's do a quick test fit of the new one to see if it's likely to work seems like it will when I was shopping for these the main Dimensions I was concerned about were the width and height of the head unit of the dro because it needs to fit in the casting but also it needs to fit in the hole in the sheet metal or at least be close in this case the height is exactly the same and the new unit is ever so slightly narrower so it will fit in the hole in the sheet metal that's a nice feature I won't have to modify anything there I might even be able to reuse this Factory bracket actually because there's mounting holes in very similar places on the back of the new unit holding it up here yes indeed actually those slots will line up the mounting hardware in the new unit is M3 instead of M4 so I'll have to use different bolts but otherwise I think it's going to work I'm going to need to cut the scale down to length you can tell on the original that is how the factory is making them they are cutting down a standard 100 millimeter scale to length and drilling holes in it for mounting I did a quick hardness check on the scale with a file to see if I can cut it I'm not sure if this is hardened steel or maybe stainless the file is in fact cutting it so this is probably stainless that's good news if it was hardened then this whole job was going to get a lot harder look these are the jokes people I gave it a shot on the bandsaw and this cut it just fine that's good news that suggests this might be 303 stainless something fairly easy to machine if this is 316 or 416 then it would be very very difficult and we would be in trouble it's not even getting warm though so easy cutting and I can easily chamfer that edge with a file Pro tip if you take one of these apart there's a little leaf spring that just fell out that holds the tension against the scale inside that leaf spring is retained with a pin in a hole there's really nothing else holding it so you have to very carefully set it in there and then use the scale to essentially hold it in place something to watch for if you take one of these apart as I said earlier in an amazing Stroke of Luck the factory bracket actually fits the holes line up and everything this new unit uses smaller Hardware so I couldn't use the original M4 bolts I didn't have any M3 button head bolts which would have been a better choice here but these will work time for another test fit I want to get this in and see what my options are going to be for mounting the bottom looks like I can't use the clamping style brackets as is that came with the new Dro I'm going to have to do something else for mounting the bottom similar to what the factory did they just drilled holes in the scale because the scale lines up essentially flush with the bracket they had some spacer washers underneath it well in amazing Stroke of Luck number two if I set the new unit in here with no bracket on the bottom in fact the scale lands perfectly flush on the surface of that bracket so no spacer washers or anything required much like the factory bracket I can simply drill holes in that scale to mount it and I won't need any spacers or trickery at all this is working out better than I could have possibly hoped this also gives me the chance to clamp the bottom of the scale to the bracket and give it a little test drive here to see if this is going to work Stroke of Luck number three the battery door even still opens I was concerned about that because this is a slide out type instead of a screw in from the front type but that works just fine as does the quill when mounted in this position it's reading correctly and the scale is long enough there I cut it to a good length and everything seems to be working great so I think this is just crazy enough to work as you can see this quill upgrade has not done anything to fix the rigidity problem of the chintzy bracket and in case you were wondering no it's not the quill as you can see here I can shake the whole Machine by the quill and nothing moves but just touch that bracket and the numbers go crazy it is definitely the bracket not the quill that's moving time to get that bracket off and have a look at what we can do about it I had low expectations for the equal attachment point but actually it's quite good there's a nice machined flat spot with nicely threaded holes so there's nothing really at issue there we can definitely reuse that taking a closer look at the bracket it's steel but it is very thin sheet metal and it's pretty clear why it's too flimsy now probably you could weld a piece of round bar in there to stiffen it up and fix this problem in 10 seconds but I thought it would be fun to machine an entirely new bracket out of solid aluminum so that's what I'm gonna do stockpile coughed up this lovely piece of bar stock that's just about perfect it's just a little bit bigger in every Dimension than what I need I love it when that happens I'm going to start by squaring this up I'm going to do this the traditional way involving rolling the part around putting reference surfaces against the fixed jaw Etc I'm not going to go into detail here I have an entire video on the traditional method of squaring up stock if you're interested check out my mil skills playlist there is another common way to do this which I sometimes call the CNC way because it's the way that CNC machines tend to do it which is to hold the piece just by the bottom Edge which gives you almost complete access to the top five sides of the part then you face the top and side Mill the four sides around that top now that doesn't work as well on small machines because when side Milling you get more deflection because small machines are not as rigid so you aren't going to get as much squareness out of the part doing that and you tend to be left with a big heavy cut that you have to take on the far side of the part at the end which again small machines aren't as good at so for squaring up stock on smaller machines I find the traditional method shown here does actually work better whatever method you use there will be a moment in the process where a particular axis needs to be brought to Dimension as well as being squared up at the same time for that rather than measuring anything I'm simply scribing the dimension off of the original part this is plenty of accuracy for this type of thing I'm just going to scribe a line and Mill down to that line by eye no need to be more accurate than that with a simple bracket like this when it comes to squaring up stock even with the traditional method however Maya one can see two laziness is that I will always side Mill the ends rather than the officially correct technical way of squaring up stock which is to stand the piece on end at this point indicate the side in perfectly vertical with an indicator because of course it's sitting on an unmachined surface then machine the ends with the end of the End Mill because doing it this way once again there's always going to be deflection when you're side Milling so these end pieces will not be quite as Square as you could achieve if you did them the traditional way but again who's got time for that since the front and back of the bracket are different heights I thought I would Mark a jaunty angle on my one piece bracket and this will make it look nice and also help give access to the screws that are going to be bolting this thing to their respective components here's my favorite trick for medium Precision if you will Milling of an angle describe the line on the part place it parallel on top of the vice jaw line the line up with the parallel clamp it down remove the parallel and Presto you can Mill down to that line without hitting the vice Jaws while I'm making chips let's talk about auto shut off I was not able to find a quill Dro digital scale linear scale digital caliper anything that doesn't say specifically that it is not auto shut off those don't seem to exist this one did say in the Alibaba listing that it is configurably auto shut off however it came with no instructions and I cannot figure out how to disable the auto shutoff So in theory you can however on the plus side at least the auto shut off on this one is five minutes instead of one minute and it wakes itself up automatically when the scale moves which the factory pm1 does not do so those two things still make it a huge upgrade in the auto shutoff Department next I need to hollow out the center to form the actual bracket my design here is that it's going to be a U-shaped bracket like the original but it's going to have solid angled side ribs along the sides to reinforce it and make it rigid so for that I'm just going to Mill out the center here and form a pocket to create the shape all at once I'm touching off on the low side of the angle because I need to know exactly how far to go downwards in order to leave the thickness on the bottom that I want I'm going to start this pocket by plunge Milling down to final depth at the highest point and then I'll side Mill out the pocket from here at least that was my plan this turned out to be a little bit too much depth for side Milling all at once on my little Mills so I ended up bringing the cutter back up a little bit and I did my side Milling in a couple of passes working my way down I milled out a channel down the center first of all and then worked outward from there Milling the kind of rectangular shape of the pocket again in a series it passes working my way down Milling clockwise around the part so that I am conventional Milling all the way around never climb Milling [Music] the way this pocket is dimensioned is pretty straightforward I had Edge found to find the center of the part then I worked out 2 plus and minus extents for the size of a pocket that would leave a quarter inch wall thickness all the way around and then of course accounting for the radius of the cutter that I'm using that gives me the positive and negative numbers to work to on the dro for both X and Y I used a fairly large diameter cutter for this first pass for rigidity and efficiency in that cut but the corner radii left by that are too large of a diameter they're going to interfere with the clamping Hardware so to finish up I came in with a smaller diameter and Mill that has a nice long reach that allows me to get in there and side Mill into the corners to shrink the radii of each corner I'm also Milling the bottom a little bit I left the depth a few thousandths shy of final depth so that I can do a cleanup pass with this smaller End Mill at the same time so once I'd sharpened up those Corners then I milled the bottom flat and bought your uncle there's the pocket onto the quill mount for this I'm measuring the factory bolt pattern the size of each and their spacing which gives me the positions of the clearance holes that need to go in my new bracket these of course I centered up once again with the edge finder and this is easy peasy lemon squeezy but only with consent I did have to find some longer M4 bolts for this because of course my new bracket is quite a bit thicker than the sheet metal one was so the short little factories bolts are not going to be long enough the factory bracket had access holes drilled in the front in order to get to these bolts but honestly it didn't really seem necessary with a ball nose Allen key it was not very difficult to get in there and then of course the short end for tightening it so I didn't bother putting the clearance holes in the end quick seat of the pants rigidity test and I would say that passes with flying colors I can shake the entire Mill by that little bracket so I think it's safe to say it is very rigidly mounted now and once again amazingly fortunately the new quill Dro scale matches exactly with the surface of that bracket with no spacer washers underneath like the factory one had really incredibly lucky I thought I might be able to use the little clip that came with the new Dro for mounting but it's actually wider than the bracket I just made so I would have had to plan ahead better for that that's okay I'll drill it through and bolt it the same way that the factory one was mounted now the real test though have I actually solved the rigidity issue with the bracket I can clamp that on there give it a little test and oh yes look at that if I Yank on it hard enough I can get a thousandth of movement out of it but importantly it always goes back to zero when I let go so we've eliminated almost all of the movement and the rigidity is orders of magnitude better really really an excellent Improvement one more quick test drive before I commit to attaching the scale to the bracket everything seems good so I think I'm ready to go let's go ahead and drill the holes to mount the bottom end of it one bolt would probably be enough to hold the bottom of that scale in place but I figured I might as well use the factory two bolt pattern because then I can put the old Dro back on if I ever need to I set this up for drilling get it centered up with the edge finder now when I line up where the hole needs to go it lands right on that shoulder where the plastic insert is that means the drill is going to tend to wander I decided I'd better come in here and make a flat spot first to keep the drill on target you might be asking well why didn't you just drill it from the other side Bend and well because shut up that's why here's where my luck finally ran out on this upgrade I was cautious about face milling and drilling this being that it is stainless I thought it was probably 303 because of how easily it cut on the bandsaw but no it is definitely not 303 trying to plunge Mill a flat spot trashed that into mail immediately I figured I had probably work hardened the material at this point but I did get my flat spot so I thought okay come in with the center drill and the drill and try to drill this through but the center drill worked okay and however the main drill no good it's not getting hot but it is definitely rubbing not cutting and it's almost certain that I have now work hardened the stainless in that hole I took another shot at it with a cheap drill that I don't care about but that is sharp to see if I could just kind of muscle my way through the work hard and top surface and finish this but nope I just trashed a second drill trying that well that's a problem for a future Quinn let's try the other side while I'm set up being a lot more careful now to get in and get out which is the secret to drilling stainless don't let the drill rub but even being very careful to not let anything rub the drill was not cutting at all again the center drill did okay but the main drill just instantly started work hardening and instantly burned the end off the drill I was really shocked how quickly this stuff worked hardened so I'm thinking it's probably 416 stainless something really ornery like that now I'm in trouble I've got two partially drilled holes with thoroughly work hardened Bottoms in them what am I gonna do I dug through my drill bins and I found this bad boy this is a solid carbide drill in exactly the right size now to be clear this is literally the only carbide drill I own and I didn't even know I owned it I found it in the back of a drawer someone must have sent it to me at some point and it was the exact right size a very reasonable question would be how do you sit comfortably with that horseshoe up your ass and all I can say is a combination of cheeseburgers and you get used to it look at that carbide go just chewing through hardened stainless like it's nothing carbide is really amazing thank you Cobra carbide for making this drill that appeared in the back of my tooling drawer somehow waiting for its moment to be the hero those holes are not going to win any beauty contests because of all of the garbage that I did leading up to switching to carbide but I got it down in the end and that's what matters you probably noticed that those drills were wandering despite all my efforts to prevent that so I ended up transfer punching these holes onto the final bracket because I know they didn't end up in the exact places where they were supposed to so if I just measure them and drill out the bracket they're not going to be in the right place so transfer punching for the win and yeah the factory Dro may not bolt on correctly depending on how big the clearance holes are but the new Dro bolts on perfectly and despite the holes being slightly cattywampus we will say that's all that matters Moment of Truth though did I actually solve the problem let's do some heavy Milling cuts and find out boy did I ever look at that that's a 40 thou depth of cut and that quill diaro has not moved even a tenth that is beautiful go back the other way doing a 60 000 depth of cut and again zero movement on that quiltyro double Imperial fist pump of victory that is huge this is the number one issue that I had with this machine and it's a huge relief to have it fixed I can finally start trusting the quill dro next I'm going to focus on the way cover this Factory piece of neoprene acts as both column and bedway cover it works okay but on the bed as you can see it doesn't keep out all the chips like something with a little better coverage than that on my previous Mill I did a thin piece of leather as a bedway cover which worked really well so I'm going to do the same thing conveniently the base of the column actually has bolts on it already which looked like they could have been for mounting a column way cover but I think actually they're supposed to be stop bolts because they have a little adjuster nuts on them however the stopping distance of the bed is set by the dro on the back anyway so those bolts aren't doing anything the leather that I'm using is 60 thou thick however leather thickness is measured in ounces it's kind of an old-timey measurement so this maps to three to four ounce leather if you're looking for something similar I found this bracket in my scrap bin that I'm going to use already got some slots in it that needed widening punch a couple of holes in the leather and I should be ready to go I'm mounting on the back of the table using the factory mounting bolts where the neoprene was then at the base of the column I've got my new aluminum angle bracket now that bracket could just be a flat piece you could Mount both the neoprene and the leather on the same locations but I happen to have an L bracket so I just used that because it seemed a little bit cleaner next I'm going to cut the neoprene shorter because if it's just covering the column it doesn't need to be as long this way it won't bunch up as much when the head is down very low when doing weight covers you want to make sure that the weight covers are not compromising table travel or head travel on the machine that can really cost you in setups the acid test of this of course is to run a table all the way back and the head down as low as it'll go more or less and there's nothing interfering with travel the travel limit on the back is still the dro scale which is good I haven't made anything worse well that is all the time I have I am sure there will be more mods made to this machine and I'll keep you posted when I do another batch but these few changes here have made a huge difference in quality of life for the machine especially that quill Mount so if you have this machine strongly strongly recommend you make that change if nothing else well thank you very much for watching and thanks to my patrons especially who make all of this content possible every single week you guys mean the world to me and I will see you next time

Channel: Blondihacks

Views: 116,276

Keywords: blondihacks, machining, machinist, abom79, this old tony, vintage machinery, steam, electronics, making, maker, lathe, mill, woodworking, workshop, shop, model engineering, engineer, engineering, live steam, machine shop, metal lathe, vertical mill, metalworking, metal shop, diy, home improvement, how to, do it yourself, do it yourself (hobby), mini mill, mini lathe, tutorial, model engineer, steam engine, milling machine mods, machine tool mods, pm728, pm-728vt, 728vt, precision matthews

Id: FxYgdNiwtzA

Length: 25min 54sec (1554 seconds)

Published: Sat Jun 24 2023