Member postings for Andrew Johnston

A few extra notes:

The R8 taper is common because of it's use on Bridgeport mills. There seems to be a rule of thumb that it struggles with transmitting much more than 2hp. Above that the INT series, and variants, are much more common as they are positively driven via dogs. My horizontal mill is INT40, but has a 5hp motor, so R8 wouldn't be much use. Knowing what I know now I wouldn't go for INT30 as tooling is rare; INT40 and INT50 are far more common.

I use the TTS tooling system on the Bridgeport and CNC mill, so I rarely swap R8 collets. I only have three, the special 3/4" one for the TTS sustem, a 5/15" one bought for a one off commercial job and a 1/2" collet. The 1/2" collet gets used with the right angle and Quillmaster heads for the Bridgeport, not for tool holding.

Most of my manual milling is done with 6mm and 10mm side holders. I rarely use ER collets for tool holding on the manual miil.They do get used more on the CNC mill. For other cutters on the manual mill I have large sidelock holders and Clarkson Autolock chuck copies.

The R8 taper rarely sticks, if it does a sharp tap is all that is needed. I've noticed that the taper sticks more on the CNC mill than on the Bridgeport. I suspect that is partly down to inaccuracies in manufacture on the CNC mill and also that it gets far less use than the manual mill. I try and leave the R8 collet loose on the CNC mill if I am not going to be using for a while.

As has been said there is no right or wrong answer.

Andrew

Personally I'd say yes. but I am biased as both my vertical and CNC mills are R8 taper. There is an argument that with MT in the mill you can share tooling with the lathe. But you'll need to have a fairly large large to have a MT3 tailstock. And I've never felt the need to swap tooling. For a start the lathe tailstock doesn't need a drawbar, the mill definitely will. You might get away with drill chucks in the mill without a drawbar, but I prefer to have drill chucks dedicated to the specific machine tool.

Andrew

Like this, on a 3.5" diameter workpiece mounted on an homemade expanding mandrel:

Andrew

Cutting parameters are over-ambitious. I use YG cutters from Cutwel and they recommend 14750rpm for a 1mm cutter in low carbon steel with a feedrate of 75mm/min and maximum DOC of 0.2mm for slotting.

By far and away the biggest problem will be maintaining a smooth, and constant, feedrate. With small cutters chip loads are a few tenths at most and it is only too easy to exceed that. It only needs to be exceeded for a fraction of a turn of the cutter to break said cutter. I hate using small cutters (<3mm) on my manual mill and do my best to avoid it. Spindle runout needs to be less than the typical chip loads.

When I made this "nameplate" in steel on the CNC mill, with a 0.5mm diameter cutter I started with cutters from Drill Service. Even so they both broke part way through:

I swapped to YG cutters from Cutwel and one cutter did both parts without breaking. I have just used the same cutter to make two nameplates in engraving brass, running at 24000rpm, again without a problem.There is no substitute for quality cutters.

I use flood coolant on the CNC mill, primarily to wash away the swarf.

Andrew

Are you using a carbide parting off insert?

If so, they are useless for grooving in my experience as they chatter badly if you don't keep the feedrate up. Which is not ideal for sneaking up on the depth of a groove. As a parting off tool they are fine, procvided you keep the feedrate going, a minimum of 4 thou per rev and preferably rather higher. For cutting grooves I use home ground HSS tools as they allow you to sneak up on a dimension without chatter and leave a good finish. Buy a bench grinder and some HSS tool blanks.

Andrew

May not be the circuit board. When my unit stopped working it turned out that the motor commutator needed cleaning.

Andrew

All my machine tools, apart from the pillar drill, have flood coolant. I never use neat cutting oil, Instead I use Hysol XF, a general purpose soluble oil. How I use coolant depends on the machine.

Centre lathe: normally cut dry with insert tooling, use coolant for drilling and some HSS tooling, and for parting off

Repetition lathe: exclusively HSS tooling so use flood coolant on steel and dry on brass

Vertical mill: never use coolant, I mostly run carbide endmills, but also run HSS cutters dry. I use WD40 when drilling light alloys

Horizontal mill: insert cutters are used dry, but mostly run HSS side and face and slab mills where I use flood coolant

CNC mill: mostly use flood coolant except for plastics and cast iron. Coolant is mainly for washing away swarf

Pillar drill: rarely used, but always dry

I don't really see the point of dabbing on cutting oil, it just generates smoke and a sticky mess around the cutting tool. A 20 litre container of Hysol XF has lasted me about 8 years, but needs replacing soon.

Andrew

You're on a hiding to nothing then.

Inserts come in a bewildering range of styles, some of which are suitable for smaller lathes and some of which are definitely not. If the steel came from a fabricator it may well be EN3 or similar. These types of low carbon steel are "gummy" and it can be difficult to get a good finish. They have a tendency to tear rather than shear cleanly. High cutting speeds and decent depths of cut (ideally 1mm or so) are normally needed with carbide.

Andrew

There is soluble cutting oil, based on water, which is primarily for cooling with a little lubrication. And there is neat cutting oil which is primarily for lubrication on high pressure cutting operations with a little coolant. Applyin a dab of either before cutting is a waste of time. All it will do, with cutting oil, is produce smoke.

With carbide lathe tooling I always cut dry, except when parting off. I use soluble oil on the lathe and run flood coolant if I need it, mostly with HSS tooling.

The part shown will be fine as sackbarrow axle, but the finish isn't particularly good. What is the provenance of the steel and the carbide insert? What speeds, feeds and depth of cut were being used?

Andrew

I considered the EZchange system many years ago for my Bridgeport, but was advised that the mill would exceed the capabilities of the holders. I now use the TTS system on the Bridgeport, largely because I also have a Tormach mill.

On the Bridgeport the drill chucks, 10mm and 6mm endmill holders and the Haimer edge finder and Centro are on the TTS system, along with some ER20 collets holders. I rarely use the ER collets, most milling is done with 10mm and 6mm cutters. I have to remove the TTS collet when using MT drills, the Clarkson clone holder, large endmill side holders and boring and facing heads. But they don't get used that often.

Andrew

I would echo Hopper's comment on gap pieces. I spent ages chasing a taper turning issue on my lathe after I removed, and then replaced, the gap piece for the first time. Turned out that I hadn't replaced the gap piece according to the manufacturers instructions.

The Ainjest attachment looks to be imperial, so i assume the lathe is imperial? I have an Ainjest attachment on my lathe and it makes screwcutting imperial threads a doddle. Especially internal and blind threads which can be cut at several hundred rpm. But it doesn't work for metric threads so I cut those the old way without disconnecting the saddle half nuts.

Andrew

The important thing to consider with a gap bed is not so much the diameter that can be turned but the length. With a faceplate in place that can be surprisingly small.

I have a 2-axis DRO on my vertical mill, and it is the most useful accessory I have ever bought. But I don't have a DRO on the lathe and have never felt the need for one.

Andrew

How much wear? Does it affect drilling holes? Drill presses are not precision tools, so unless the wear prevents holes from being drilled I wouldn't worry about it.

Andrew

Standard on Kurt vices, although thus far I've never needed to use the feature.

Andrew

Forgot to say that for the trial cuts I used a 6mm square HSS toolbit that came with the boring head.

Andrew

I've been playing with the Kuroda boring head on the Bridgeport this evening, boring and facing:

All functions seem to work and the head is a joy to use. Put on a 0.025mm cut and as near as I can measure the hole diameter increases by 1 thou (I don't have any metric internal micrometers). it was simple to get the hole diameter to size within a couple of tenths, on the micrometer reading at least.

I like using nice tools.

Andrew

That would be my guess as well. Plus, the slide screws are not going to be precision ground, so a thou or two error is probably to be expected from a low cost product.

Andrew

Tool needs to be turned through 90 degrees.

I never got on with flycutters for producing "flat" surfaces: I prefer face mills. I use a homemade flycutter only for creating curved surfaces:

Andrew

I never really got on with my budget Soba boring head for the Bridgeport, hence the Kuroda purchase. The socket head grub screws (Whitworth thread) were poor quality and have been replaced where possible. I found it difficult hold a tolerance as the adjustment screw was quite sloppy.

I have used insert boring bars with my Wohlhaupter boring bar in the horizontal mill. But I had a lot of trouble with chatter and a poor finish. To be fair I was pushing my luck on the length versus diameter of the boring bar. But I don't think boring heads really run fast enough to gain benefits from insert tooling. In the end I reverted to boring bars with HSS tool bits with the Wohlhauper:

With a HSS toolbit it is easy to control the shape of the cutting edge and the reliefs.

With the Soba head I found it to be a crap shoot as to whether one could hold a diameter to a few thou. Whereas with the Wohlhauper, and I hope the Kuroda, holding to less than a thou is straightforward.

Andrew

Addendum

Over the past few months I have continued to look for a boring and facing head for my Bridgeport mill, without much success.

Recently I looked at a Wohlhaupter UPA2 head, but it didn't have any accessories and had an integral Morse taper shank. The seller also used the "I don't know anything about this" routine when asked if it was in full working order. I then looked at a Wohlhauper UPA3 head in excellent condition with a full set of accessories and a helpful seller. But sadly it had an integral MT3 shank and I couldn't think of a satisfactory way to replace the shank without a lot of work, and devaluing an expensive item.

Then I lucked upon a Kuroda UFB-3-F head with an R8 shank and a full range of accessories. A big plus was that the seller was 15 miles away. After an exchange of messages I went to look at it yesterday. The head is in good condition, plus the seller was a professional machinist and clearly knew his way round the unit. He had bought it from his workplace so also knew it's history. The upshot was that I agreed to buy it and he let me take it away on a promise of paying today. Here is the box of goodies:

The only downside is that one of the sleeves has been split, although it is still usable. The extension arms look to be unused and it even comes with the tapered lever for pulling and pushing the various pins in and out. Everything seems to work as it should and there is no evidence of any crashes. Of course the acid test is to run it on the Bridgeport, which I will do later this week.

I'm not going to say how much I paid as it will probably upset some people. Let's just say I fall into SoD's category of those who like to own, and use, nice tooling and am fortunate enough to be able to afford it. No significant other to stop me for a start!

Andrew