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Member postings for jonathan heppel

Here is a list of all the postings jonathan heppel has made in our forums. Click on a thread name to jump to the thread.

Thread: Morse taper limits ?
23/11/2013 09:34:10

I agree. TPXX insert cutters do work, but more by beating the workpiece into submission than cutting it. They are quite hard on the machine, and are better suited to larger mills. There are cheap APMT positive cutters around, but I've no idea how good they are. You didn't say what your machine is, but even on a solid one I'd use max 40mm on steel and 50mm on Al with MT2

Thread: Copper bit
21/11/2013 18:05:10

I think there's a misunderstonding here. While I'm sure it doesn't need to be oxygen free tig welding grade, pure in the sense of being unalloyed is most suitable.

Thread: Lugs or Spigots - Your vote!
21/11/2013 11:24:05

I have a small collection too, most of which is entirely redundant. I use the .0005 lever DTI by far the most, which I usually hold on the spigot protruding from its rear. This provides the greatest clearance from whatever I'm testing. As for the plunger type, they're used seldom enough that it's a matter of what's convenient at the time, though I keep a 2" one mounted near the headstock for saddle travel. In short, I feel that while standardising has a certain attraction, the time you'll save is minimal compared with the time spent on modification.

Thread: Morse taper limits ?
21/11/2013 09:16:13

As you said, it is a string length issue, but here's a few points to ponder.

I don't think that Clarkson's choice of 16mm/ 5/8" for its small chucks was entirely arbitrary, since they were designed when MT2 was common on quite big machines such as Bridgeports. Even then, some such chucks had stiffening rings that gave extra support. There's a law of diminishing returns dependent on variables such as workpiece material, depth of cut, feed rate, length of overhang from spindle, general machine rigidity and condition, and cutter material and type.

I believe that the maximum recommended end mill diameter for the fairly solid VMC/626 is 20mm, which is not that different from Clarkson's 16mm

Integral shank end mills, which are the stiffest of all, are seldom more than 25mm.

Face mills and fly cutters have much less overhang, so less leverage and as a result can be bigger without causing problems, but I feel that 40-50mm in steel is a practical maximum.

The huge cutters you mention IMO exist largely because there is a market for them, and not for their actual utility. As for collets, I can imagine someone having a chuck to fit a set that they already had, and only using the smaller sizes,

I expect there will be many who disagree, but this is my take on it.

Ps. I' m talking about my experience on a very solid Hayes. Modern mini-miils etc have nothing like the same capability, so sizes will need to match accordingly.

 

Edited By jonathan heppel on 21/11/2013 09:53:56

Thread: Tool chatter
18/11/2013 17:34:16

Loose slides too.

Thread: Inverter
16/11/2013 10:24:42

There really isn't a need to over specify a quality inverter. The manufacturers know what they're doing.

Thread: Decent vernier height gauges ?
16/11/2013 10:19:21

Just want to say that I am in no way against digital devices, and that there is some really quite good kit coming from a few Chinese manufacturers, though by no means all. If I gave the opposite impression, it was because I was defending my belief that ultimately electronics cannot be expected to have the same longevity as more traditional kit. I also championed their ease and speed of use in an earlier post.

I can't easily see a vernier, so I wouldn't have a height gauge, but on the rare occasion I want to measure anything over 12", I love to dig out my 25 quid Etalon 21* verniers and jeweller's loupe.

Verniers tend to be overlooked, and as a result there are some fabulous bargains to be had. You have to spend a great deal of money for similar but more modern quality.

Thread: Inverter
15/11/2013 23:09:56

Your 2hp vfd thinks the1/3 hp motor is 2hp. If for example the rotor locked, the vfd would try to produce the current for a 2 hp motor, and fry it. Overloads or fuses between them could prevent it, but then you run the risk of blowing up the vfd- they really don't like having the load disconnected while running.

It's not hugely dangerous, but a drives pro wouldn't do it.

15/11/2013 22:48:41

Alan, yes sure. As I said earlier, it used to be the manufacturer's recommendation, and is still good practice, particularly with budget drives and older non-vfd rated motors.

15/11/2013 22:42:18

Paul, what you're doing is fine as long as there isn't an overload any time. A DOL starter has thermal protection. Your small motors don't, and fuses aren't recommended for the drive's sake. You may well be fine for ever, but it is a potentially dangerous set up.

15/11/2013 22:30:42

Still no problem. The reason for the manufacturer's advice to use a motor one size bigger had to do with the spiky nature of the output. By all means use the 1.5 Kw motor.

15/11/2013 22:02:14

No problem, though it's wise to programme the motor's characteristics jnto the inverter. Most important is the max current to prevent motor overload. The advice used to be that the inverter should be one size smaller than the motor, but I think that advice is now obsolete.  Ps it probably depends on the make of inverter. They're not all the same, but probably not different enough to matter greatly. Get the best you can afford.

Edited By jonathan heppel on 15/11/2013 22:13:25

Thread: Decent vernier height gauges ?
15/11/2013 13:54:12

Why challenge a true statement?

Also, vernier has become vernacular of very vague veracity for various diverse devices

Edited By jonathan heppel on 15/11/2013 14:06:13

15/11/2013 10:59:59

There's also the issue of lead free solder, which has much lower longevity and reliability than the old sort. It's no surprise that leaded solder is still permitted for medical, military and aerospace purposes, and that solder joints are being designed out where possible.

 

Edited By jonathan heppel on 15/11/2013 11:32:09

15/11/2013 10:25:52
Posted by Brian Warwick on 15/11/2013 00:33:29:
Posted by jonathan heppel on 14/11/2013 21:24:28:

It's wise to regard any electronics as essentially disposable, even premium brands.

WHY?

To me that's a strange statement, I do not wish to be offensive but I am totally at a loss as to why anyone would make such a wild statement with no explanation.

Not wild at all When they go wrong they are frequently either impossible or uneconomic to repair, particularly when a few years old. No different than most modern electronics. Check out Long Island Indicator Repair for authoritative though not infallible advice.

I'm not suggesting you shouldn't buy electronics, just not to treat them as heirlooms, My Mit calipers gave up after ten years or so of sterling service, so I bought new ones. That's it in a nutshell.

14/11/2013 21:24:28

Most of those old timers were top quality. I suggest you look for a satin chrome or stainless one. Bear in mind speed of use- that's where the digital or dial ones score, particularly with a complex layout

It's wise to regard any electronics as essentially disposable, even premium brands.

Rotagrip advertise a reasonable looking twin column dial type.

Me? I use an APE microball, which is yet another style. 

Just trying to cover a few bases!

Edited By jonathan heppel on 14/11/2013 21:32:02

Thread: Boring bar or threading tool?
14/11/2013 20:39:30

"Fraid so. If you want a two-in-one, you'll need to do it the old fashioned way with HSS bits, and save yourself a packet too.

Thread: Dimmer Switch
14/11/2013 15:16:39

It's a bit late to say it but just going by the power rating and ignoring efficiency, that pump is a little smaller than a "proper" suds pump, so its flow may need no adjustment anyway.

Thread: Help regarding choice in milling machine please
12/11/2013 23:45:00

I wouldn't worry about rigidity. Generally, a concern with round columns is position repeatability on the z axis, but there's a key that's meant to see to that. You may well find lack of a knee a nuisance when tool changing, and the high minimum speed a handicap also.

That said, it looks like it's excellent for high speed fine work. so I guess it depends what you're doing. Personally, i'd prefer a knee mill.

There was a thead on another Senior mill here a few weeks ago, which may be worth a look.

The myford and denford 626 and 836 may be worth looking at too. One issue with the 626 and 836 is their provenance. While there are many happy owners, there are also a few horror stories on the net also, often to do with warped castings. Proper stress relieving is an expensive process.

Thread: Bridgeport one shot lube repair, plus lubrication question
12/11/2013 22:22:03

Have a look at 4mm nylon or polyurethane pneumatic line.

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