A bit of a milestone reached this evening as it’s almost ready to reassemble. I just need to cut some lengths of M6 studding to fasten the bottom slide bars on with. Then once the basic carriage is reassembled and fitted on the ways, I need to mark out, drill and tap the carriage lock before reassembling the cross and compound slides.
There wasn’t a lot of depth and I wanted them countersunk to retain as much cross slide travel as i can also I doubt if these will ever get unscrewed again once finally fitted so I used M6 button headed cap screws instead of the usual deep headed type.
This is what it will look like when all fitted together.
The end support piece and the bottom of the carriage lock are made from the same piece of bar (eBay purchase) and must be free machining as recommended by Mike Evans, because they machined, drilled and tapped so much easier than the steel that I made the other parts from.
Next comes the most daunting part so far, machining the carriage casting to square up the cut outs in each side to take the extension pieces which will support the carriage stop.
Being a casting, the very nature of it is rounded corners and rough finish. At the very least the faces needed flattening to take the machined block which is to be let into each cut out. As I was studying the cut outs to determine how best to machine them, I noted that at the side where the inverted V was machined into the base there was a distinct slope to the edge of the cut out.
When I check this with a protractor it was almost 80 degrees. There wasn’t enough casting left to make this edge vertical without cutting into the inverted V so it made sense to machine this edge to 80 degrees. I reasoned that cutting the opposite edge to the same angle would also help relive any potential stresses on the M6 screws that I plan use to fasten these infill blocks to the carriage, when the lock is tightened down.
I then machined the ends of the infill blocks to suit the angled cut outs.
All this was made less stressful by the knowledge that a replacement carriage casting is only £23 plus P&P.
Although I have been waiting for delivery of various bits of metal and fixings which have been trickling in over the last few days (I have everything I need now, I think or should that be hope). I haven’t been idle.
I got the stainless steel lock nuts for tensioning the Gibs on the two slides and managed to get those ready to refit.
The last photos also show an anti backlash nut/block which I hope will take out the backlash from the cross slide lead screw. It’s an idea I got from the US YouTuber that I mentioned (username of Dr Jim) who made his from oil impregnated bearing bronze. I looked into getting some and nearly had a heart attack so settled for testing the concept in acrylic as I had seen another person do who had fitted anti backlash blocks to a home made CNC Mill.
Whilst making the anti backlash nut/block was quite simple. Finding out the thread size/pitch was a bit of a challenge and I am grateful to members of the Model Engineer forum who between a few relies gave me the information that I needed to work it out.
Why was it so difficult you might ask. Well, I have previously mentioned that the machine is imperial but fitted with Digital Read Outs on the cross slide. From what I have read, when fitting the DRO kit’s the lead screw is replaced as part of the upgrade. I rang Chronos who are the supplier of DRO kits in the UK who told me that the lead screws included in the kits are metric. On this basis it seemed logical that the cross slide leadscrew may in fact be metric.
As you might imagine a query on the ME forum elicited quite a few helpful answers and a few less than helpful ones thrown in for good measure. Ultimately I was pointed in the direct of a US site and advised that some of the machines actually came factory fitted with DRO’s and they retained imperial lead screws. With the help of replies that were specific with information I finally worked out that my cross slide leadscrew is a left hand thread 3/8″ 20TPI. Part of my difficulty was that I had no idea of how BSF threads were actually measured as I have never had cause to buy or measure any BSF fixings. All my experience has been in Metric or for modelling purposes, BA screws etc. Where we specify the whole thread length.
A set of taps was duly ordered from RDG engineering supplies (£10.96 inc. postage) and the job was done.
A friend who models in 4mm scale asked me if I would draw up some injectors for GNR tank engines (J52/53) so in between working on the lathe improvements while waiting for bits and pieces to arrive through the post I had a go.
He provided me with an annotated photo to work from which didn’t have every dimension on it so while I don’t think that it’s 100% accurate, it’s good enough for small scales.
Of course we need a handed pair which was the last job.
For my birthday/Christmas present from my Son last year, I received a Stuart Models 10 V Stationary Steam engine Kit. Although I knew it was coming they didn’t get to visit us until yesterday so I have only just got my hands on it.
Saying it’s a kit is stretching it a bit in terms of the kits that I am used to in 7mm modelling but I don’t know how else to describe it.
Here is what you get in the box
Last but not least the hardware and sundries in the form of nuts and bolts, gaskets etc.
I had a first go at Fly cutting with the mill last night. The pieces of bar in the last post are what’s known as hot rolled steel. Hit rolled steel is the cheapest way to buy steel but you do get an outer coating of oxidisation and the edges are far from flat/square
For the two larger pieces I needed to square up the edges and then flatten one face. I had two options use an end mill or fly cut them. I used an end mill on the edges bt for the larger area it would have taken a fair amount of time to flatten it with my largest end mill with is 10mm. With a fly cutter I could do the whole area in one or two passes at each cutting depth. The other thing that appeals to me about fly cutting is that it uses a piece of tool steel similar to a lathe tool and is something that I can confidently re-sharpen in the workshop on the grinder. I have no means of re-sharpening end mills so they become quite expensive consumables.
This is the fly cutter in action, it was spinning at 740 rpm and I was taking off 0.04mm per pass
Now onto a scarier upgrade. This is the bottom of the main carriage.
The two black strips that you can see screwed to the underneath of the carriage are hardened steel and they stop the carriage from lifting. As you can imagine the needs to be a bit of clearance between these strips and the underside of the carriage to allow it to slide along the bed of the lathe. As delivered this clearance is adjusted and fine tuned by the set screws and locking nuts that you can see between the cap screws. As I understand it these lead to cracking of the hardened plates over time.
I have seen a few ways to over come this but the best way that I have seen is to remove these grub screws and replace them with an appropriate thickness of brass shims. The person I saw who added shims just had lots of bits of shim balanced in between the two surfaces but a Gent in the US improved upon that by making a jig to drill out the shims to match the hole spacing of the main cap screws thus preventing them from being dislodged while being refitted to the lathe.
Next is to replace the cap screws with stainless studs and nyloc nuts and then remove one of the hardened strips and replacing it with a mild steel strip of more substantial proportions.
There are a couple more bit’s of material that I am waiting for so the rest of the description will have to wait until then.
But in the meantime, the next job is to mill out the carriage where the blue blocks are to take the two pieces of square stock in the image these will be screwed to the ends of the carriage in the milled gaps and will form the anchors for the carriage stop.
When I picked up the new lathe and gave it the once over I noted that there had been some upgrades carried out already which rather surprised me that whoever had done it hadn’t fitted a carriage lock etc. One of the other recommended improvements that people make is to fit a swarf guard to the back of the apron (for those that don’t know what an apron is and I didn’t it’s the gear housing for the carriage hand wheel which also houses the auto feed mechanism). Most people that I have seen make such a cover have done it from thin perspex sheet which works fine but I was delighted when I saw that mine had a brass cover.
I was even more delighted when I took it to bits and found out just how well it had been made. You will also note the grease nipple. Grease nipples have been fitted to all the bearing housings.
Prior to buying the lathe I did quite a bit of research and one of the things that I picked up was that in being made to a price, these Chinese mini lathes lack the rigidity of their bigger higher end ‘professional’ cousins. What quickly became apparent though was that they can be made much more rigid for the outlay of some time and very little money.
What the Unimat had but the Sieg hasn’t, are the means to lock the carriage, cross slide and compound slides. I have already attended to the latter two by drilling and tapping more M4 holes along the Gib strips.
I did the compound slide first, you can see the new holes by the remains of the marker pen that I used for marking out.
Then the cross slide, I didn’t need as many additional screws on this one as it was already supported towards the end of the Gibs
Two screws on each slide wont have lock nuts on them and they will act as the locks when tightened the rest will have grub screws and locking half nuts to position the Gibs to allow smooth travel of the slides.
Prior to Christmas I had decided that the week between Crimbo and the New Year I would spend ironing out the wrinkles with the new lathe.
First I stripped down, cleaned and deburred all my chucks which you can see in the photo of my workbench in the last post.
The lathe came with two 3 jaw chucks (80mm and 100mm) and a 4 jaw chuck. I have seen a few reviews on YouTube of Chinese import chucks and it seems that although basically sound bits of kit, to keep the price down they don’t do any cleaning or deburring post machining which means that many of them have all the grinding dust present inside which if mot cleaned out will drastically reduce the life of the chuck.
The 4 jaw chuck cannot have been used because when I tried it before stripping it down to clean one of the jaws wouldn’t actually close due to burrs in the slides. I also took the opportunity to strip down and clean another 3 jaw 80mm chuck that I had bought in October with my rotary table for the mill. The latter is actually the best manufactured of all of them needing very little to getting running smoothly. Next up was the ball handle for the compound/top slide. I didn’t take a photo of it prior to starting work on it but it should look like the one on the left (from the cross slide)
I am not sure if the handle had been broken off at some point or just crudely sawn off but I wanted to replace the handle part. I am pretty sure that I could probably buy a spare from Amadeal but where is the fun in that. So I made a fixture out of an M10 cap screw a couple of nuts and some washers to hold it securely in the milling vice and drilled it almost to the bottom. I did consider that I might have to drill it right through because I didn’t think that I had an M6 plug tap but I found one in a drawer so I was able to retain the chromed ball.
The plan is to make a handle similar to the other one from stainless steel rod once I get the lathe back together.
A post on Western Thunder asking for photos of members work spaces tempted me to take these and subsequently share them here.
To the right of my first image showing the the bench, the upper cupboard door houses my spray booth and working back from there is a small worktop with my Ultrasonic cleaner and then a sink with drainer taking up the remainder of that wall.
A while ago when making the improvements to the tail stock of the Unimat, I mentioned that I planned to make a machinists hammer.
Well, I made a start and ,machined up the body of the head the screw in faces, and the shaft but hadn’t done anything about the handle by the time I sold the Unimat.
Primarily this was because I had struggled to thread the 8mm stainless rod that I used for the shaft and was awaiting delivery of a new set of metric taps and dies to complete it. The taps and dies duly arrived but by then I was on with other things so it was being used just with a the bare rod as a handle. I had managed to thread the end that fits into the head it was the handle end that I had struggles with. About 3 weeks or so ago I got around to threading the handle end of the shaft but was undecided as to what to make the handle from. I had a choice of some 16mm diameter aluminium rod or some of the acetal rod that I had made the faces from. which is just over 20mm diameter. In the end I opted for the acetal. but it wasn’t until yesterday that I got my finger out and made the handle.
Having drilled and tapped it 8mm. Instead of knurling the acetal rod to create the grip, I decided to turn concave grooves using a HSS tool bit that I had ground into a curved end but hadn’t tried out on anything.
Once that was done it was just a case of fitting them together. In the end I had to cut a few threads of ether end to ensure that no threads were visible where the shaft enters the head or handle as I hadn’t really thought too much about how much thread I was creating versus how deep I could actually tap each piece.
Aside from regrinding a few tools to sharpen them, this is my first real go at grinding a tool from a blank to create a particular shape. My plan with this one is to have a go at turning a chimney at some point.
Once I screwed the faces onto the head and the handle onto the shaft I couldn’t get them off again without risking marking them up so I wasn’t able to take any photos of it further disassembled.
This is the finished hammer which has turned out rather better than I had hoped when I started out. It’s main function will be to ensure that materials are seated properly in the mill vice of lathe chuck but I am sue that I will find other uses for non marking brute force….
Onward with part II, a step by step of how I made the next lot. In this instance I needed 3 L shaped lamp irons as opposed to the slightly off-centre T shape of the earlier efforts.
It may be a bit of a photo overload as I probably took more photos than needed to get across the methods used.
First I cut of the insulated section of another plug pin.
I fastened it in the milling vice supported on parallels and lowered the quill until it just touched the work piece and rotated it by hand to establish a base height for cutting.
Then I set the dial on the fine feed to zero
Here we are ready for the first cut, you can see the parallel sticking out the end of the vice. To get the right height I had to stack two different sizes of parallels on top of each other. – in this instance I used a 5 x13mm on top of a 6 x 24mm. I have a set of 20 pairs of different heights and thicknesses. I have also cut a couple of cheapo 6″ steel rules in half for if I need really thin parallels (the thinnest in the set is 2mm thick)
Next we start to take the first cuts to form the back of the L using a 5mm 4 flute end mill.
Once I got to the lowest depth of cut that the top of the vice would allow I moved the cutter back to take a small cut to create the underside of the lamp iron. I only took a couple of passes just so that I had enough of a ridge that I would be able to see the slitting saw passing through it in a later operation
Then I used a small brass hand vice as a vice stop to allow me to turn the part over to do the same on the other side.
Next I shifted the part so that it was fixed in the end of the vice with the upper leg of the L stick out of the edge of the vice horizontally and made the first cut with the slitting saw.
This is at the end of the first cut. The slitting saw is the 4″x 0.5mm 100 tooth blade that I used for the first ones.
Once both the slits were cut I put the part back in to the top of the vice to cut through the horizontal leg of the L with a 3mm four flute end mill
I had inserted a small brass shim that gave me another 0.7mm of clearance above the vice jaws which allowed me to mill down until there was only a sliver of brass holding the parts in place
Finally I was able to just touch the lamp irons with a scalpel blade to lift and cut them free.
All that remained was a bit of hand filing to finish them off ready for fitting
Finding myself at the point of fitting lamp irons I was muttering about fold up etched version provided in kits and the fact that I ould buy some cast ones from Laurie Griffin et, al but I only needed 3 of one type and a couple of another. Then I recalled having some milled angle with one leg longer than the other which I had used for replacement step boards on the Slaters LNER brake van. I was sure I had some off cuts but they are stashed somewhere safe so while they resurface I thought about the more conventional type. I had once seen some made by silver soldering a strip at right angles to a another to recreate the shape when sawn of in strips but couldn’t find the page that I had seen it on.
This brought to mind why don’t I mill some. When we moved we had a drawer full of 13 amp plugs that I had removed from appliances before binning them. Knowing that we would never use so many plugs I took them apart and removed the pins (solid brass) for potential future material and binned the rest. Fortunately I knew exactly where they were so I set to this evening and milled one to shape.
Once I had the basic shape I then cut it into strips using a razor saw. Having proved the concept next time I make some I will use a slitting saw. I had thought about using it on these but didn’t think that the milled shape would stand the cutting forces.
Following on from my making of the replacement carriage lamps for the Brumm Carriage acouple of posts or so ago, I decided that I really couldn’t live with that bright yellow livery.
So, in between other jobs, I carefully took it to bits and resprayed all the bits to take off the ‘plasticy’/toy like look. This journey was helped by my sorting out the issues with two of my airbrushes and completely killing the third when the spray nozzle broke off as I was reassembling it after a thorough clean. I have kept the remaining parts as I am pretty sure that the needle and other bits will fit one of the others.
I originally wanted to finish it in a crimson lake colour but I didn’t have any paint to hand so I enlisted Chris’s assistance to mix some. Part way through that process she arrived at a lovely plum colour which I rather liked so we stuck with that.
I do still need to fit those replacement carriage lamps though…