Member postings for Kettrinboy

Hi Ron

Rather than dial the speeds up I would try them quite a bit lower , for say 20 mm aluminium with a HSS tool try 250-400 rpm , and for the freecut steel the finish you got in the photo is okay for roughing down with an indexable tool but to make sure of a fine finish on steeI I always use a sharp HSS tool with a decent thin cutting oil , this works even on difficult stuff like EN3B and the speed for 20 mm dia would again be 250-400 rpm , a lot of novices think the answer to bad finishes or tools not cutting is to whack the speeds up when they would be better off trying lower speeds ,but too high speeds even on aluminium can quickly knock the edge off HSS tools and as said before if you want to get a good finish on a light cut with indexable tools you need the ones with proper sharp edges , the less sharp variety will just push off on a light cut and give the sort of finish in your pic, the lower speeds will be kinder to the lathe as well , the faster you run it the more it will tend to vibrate compounding problems with finish.

regards Geoff

Edited By Kettrinboy on 25/01/2019 09:13:30

Heres the "big tool " I used to work , this is circa 1985 I was 22 yrs old and a couple of years out of my 4 yr apprenticeship and happily working in the turning section of a printing press maker in Kettering , then I was asked to train up on this beast because the bloke who worked on it was leaving , its a milling machine converted from a big planer , made by Futurmill a firm based in Brighouse Yorks , table size 12 ft by 5 ft and a 50hp motor , with the 8 inch facemill which you can see fitted a roughing cut on cast iron which is about the only material this machine ever did was full width of the facemill 1/4 inch depth at 30ft p/min feed , its max was 50 ft p/min , this machine did all the preliminary milling of the baseplates and sideplates for the presses , typical size of a baseplate was up to 6ft square and after the top and side surfaces had been milled (you can just see the side head behind me ), then a load of drilled and tapped holes ranging from M5 to M30 had to be done , when I first did an M5 hole I thought how can this massive thing do a tiny thread like this, but by using a sprung holder and getting used to using the fine controls on the pendant it became everyday stuff , sideplates were typically 4-6 ft long and 3-4 ft wide by 2-3 inches thick and the tolerance on all thicknesses was +/- 0.002" which it would pretty easily get to ,I worked on this machine for 6 yrs and I am glad I used facemasks from early on with it as the black CI dust produced was horrendous , every day you needed a new mask as a new mask put on in the morning would be black on the outside by knock off time, I don't know if its still working today as I left the firm in 1990 and havnt been back since so I might have to have have a peek in the shop sometime as its only down the hill from my house.

regards Geoff

Hi Ron

what sort of bad finish are we talking , vibration marks or surface tearing of the material ? , as the lathe was doing good finishes before the mods you have done to the drive recently may have introduced some vibrations that were not there previously or surface tearing suggests a tool angle or cutting clearance problem, when I grind a tool I get the magnifying glass on it to check the cutting edge as its easy to get in particular the side rake a bit too vertical so then it wont cut well or give a good finish , also after grinding its usual to stone the tool to finish it and that can also lose the sharpness and clearances if not done with care.

regards Geoff

Don't think anybody's mentioned it yet but whatever way you set a precise angle on the top slide it wont be cut precisely if the tool is not set dead on centre height , if its out either way the angle cut will not be exactly as set.I found that out when I used to have to machine a precise 20 deg angle on water pump impellers for Mercedes F1 engines.

regards Geoff

To the OP don't be afraid to skim up the face of your 4 jaw chuck if its out at all, a couple of thou runout is too much if your trying to get faces on a block parallel and square, done the once it should stay true for years.

regards Geoff

Hi Iain

Looking at your flywheel on the other thread you could perhaps incorporate some weights in the flywheel as well as on the crank webs as you might not be able to put enough weight just on the crank itself , but some on the flywheel as well might help , heres a pic of a flywheeI I made , the weight is held by a single screw and can be modified in size , I think balancing although you can calculate it to an extent , in practice it is just trying different weights in different positions until you get it to an acceptable level.

regards Geoff

To the OP how old is the lathe and how much work might it have done , I worked on a Triumph 2000 for 15 yrs in a very busy sub contract shop and when you think how many thousands of times the tailstock has slid back and forth including in its previous life before we got it I expect enough wear could occur on the bed and tailstock ways to drop the centre height a bit especially if the bed hasn't seen much oil in its life or has been lubricated with suds , shimming is a perfectly good way to bring it back though if its gone below the headstock centre height.

regards Geoff

Edited By Kettrinboy on 27/11/2018 17:03:38

I would run a dti across the crosslide top surface in both axis to check for distortion or for slope , out of interest I just did this test on my 1963 Harrison L5 crosslide and the total indicator reading over the whole crosslide slide surface was 0.01 mm which is about what I would expect , I would get in touch with Warco and just ask what the shop tolerances are for the crosslide ,and if yours is significantly worse what can be done about it , I know Harrison back in the day for example sent each new machine out with an inspection test sheet with all the parameters checked against shop tolerances.

regards Geoff

Edited By Kettrinboy on 27/11/2018 09:20:25

Sean ive got a 4 piece ball type set and find the two bigger ones that go from about 5mm to 13mm are pretty easy to get the right feel and the measured size with a mic is within about 0.01mm when compared with using a precision plug gauge ,so I use these a lot ,but the two smaller ones that do 3 to 6 mm are a bit more tricky to get the feel of because they spring a bit and getting a definitive mic reading is more difficult so I would still rely on plug gauges to err gauge the exact size of a sub 5mm hole, but as they are relatively cheap I think they are well worth getting.

regards Geoff

Edited By Kettrinboy on 25/11/2018 09:16:43

Ron regarding the single grubscrew to lock the table you might be able to make a simple mod to improve it by adding another screw at 180 deg to balance the clamping forces out , my MES rotary table had one small screw to lock the table and usually pushed it 3-4 thou out which is just too much for precision work so I drilled two opposed holes with a bigger thread at 180 deg and made two small ball ended levers which are miles easier to use than faffing about with two spanners and the result was with a clock on the spindle doing the two clamp levers up simultaneously only 5 tenths of a thou deflection so well worth doing.

regards Geoff

Edited By Kettrinboy on 23/11/2018 18:14:37

I,m with clogs on this one as I said in another thread a few days ago ,if you want it to look pleasing to the eye its easy to make a rounded top key from some flat stock by using an edge rounding milling cutter, so say for a 6mm wide key a pass either side with a 3mm rad cutter forms the round top and a bit of fitting with a file fits it in the keyway , so compared to the lathe method it takes a bit longer to make the key but way less time to do the keyway.

regards Geoff

Your lathe looks to be a 140 and not an L5 , while the bed and carriage are similar looking between the two machines the headstock on a 140 is a different shape, ive got an L5 btw.

regards Geoff

There are quite a few useful parts in old printers , when I junked my last one I got a couple of 6mm rods which were chromed and precision ground , I used one for the displacer rod on my rhombic drive hot air engine , it was solid so to reduce weight I drilled it through from both ends to give 0.5 mm wall thickness , it drilled very easily so must have been a freecutting steel and stayed dead straight so has worked out perfectly for this engine.

regards Geoff

There is a quick and easy way to do keyways in shorter lengths , just clock the centre of the hole on a mill and plunge an accurate sized cutter to the size of keyway you want down in steps until wide enough for enough key engagement , much quicker and less fiddly than doing it in a lathe , yes the top of the keyway is round but in most instances this doesn't matter, you make the height of the key to just fit in to stop lifting , heres a pic of a pulley with a 3/16 keyway only took 10 mins to set up and do.

Edited By Kettrinboy on 01/11/2018 09:03:16

Just make sure before you switch on to double check that everything clears the bed and double check you've tightened all the clamp bolts and that they have enough thread engaged , 2mm of thread engagement in a nut is not enough under load, after doing loads of set ups like this over the years I had my first prang the other day , I was modifying a tool holder for my Kennet t&c grinder and had a 3/8 plug gauge pushed in a hole to depth mic to and got distracted , didn't notice it in there before I switched on and bang the plug came round hit against the bed and broke off a chunk of the cast iron boss it was in , luckily no damage to bed and part could be modified , shakes you a bit though I must admit but things like this stop you getting complacent which can happen when you do things for ages and think you know everything.

regards Geoff

Hi Ron

For milling aluminium alloys consider getting some roughing cutters or ripper cutters ,they make a big difference as they put less load on the machine when you have larger amounts to remove , then just use your normal cutters for finishing , the steps between passes you are getting is proof of the misalignment you found while tramming the head , I would think around 2 thou or better total indicator reading over a 5 inch sweep should be achievable with some fiddling , that should be good enough for most model engineering work.

regards Geoff

Once the handwheel /dial assembly is adjusted properly so that there is no movement there the crosslide will probably still move slightly due to wear in the screw and nut , on some lathes the nut is split so that you can close it slightly to take up wear , I suppose 10 to 20 thou of backlash is pretty common on a well used lathe that's about what my Harrison L5 shows but this has a split nut so I could improve it when I get round to it, how much play is too much , I would say over 60 thou is getting towards the top end of what I would live with , but with no split nut or any way to split it and close it a bit , your only recourse is a new screw and nut or a good secondhand one.

regards Geoff

Edited By Kettrinboy on 23/09/2018 19:31:01

I,d go with what others have said and always use a quality lubricant ,it really does make all the difference , especially on the small BA taps, you say the steel is maybe EN8 but if its actually something else its quite feasible for a less than sharp tap to jam up in a deeper hole, if you keep having problems try a different tap , ive got several taps of each size and one usually cuts better than the rest .

regards Geoff

Ok Neil I understand why you had to remove the pic ,instead Frances could join the yahoo Dore -Westbury group and can then download a pdf file of the rotary table directly from there.

regards Geoff

Ive found the drawing you need on the Dore Westbury yahoo group , I took a screenshot so I could download it to my album as a jpg file , so save this pic and then zoom in to see the details .

regards Geoff

<Edit> afraid I've had to remove this as I understand the MES deigns are likely to be sold commercially in the near future. Perhaps Geoff can help Frances out direct? - Neil

Edited By Neil Wyatt on 13/08/2018 09:24:55