Member postings for Ajohnw

I'm about to make a powered spindle for use in several modes. it's currently in thought mode. I have a motor out of sheep shearer. Might be easy to find these in some parts of the world. It's a 180v motor that's used with a small electronics box to regulate the speed even under load. The output power is 1/8 hp at 2,500rpm, some what more than the small sowing machine motors as they specify the input power on the ones I have seen. It's a permanent magnet motor. These tend to be more efficient than others. The external magnetic field is pretty low but will still collect bits of magnetic metals if I allow them to get to it. Not that this matters really as it's totally sealed. A shield of some sort should minimise that problem.

I also have another rather powerful sheep shearer motor. Bit big for this sort of thing. I assume the smaller motor is for a light weight portable one. It was made by Fracmo, 5 1/4" long and 3" dia, 168w in for 90w out.

There are some different sewing machine motors about now that come complete with an electronic drive. Either fixed speed or variable via an inverter. They appear to be brushless types of some sort and start at about 1/2hp in and are pretty compact. They probably give at least 1/4hp out. I don't fancy the cost but may go that way if the sheep shearer one doesn't work out.

John

-

The Canadians bemoan their shipping costs to the UK. I've had several sellers really try to get it as low as possible but it usually make the purchase just too expensive compared with other countries. The US has USPS. Probably the cheapest overseas shipping company in the world - if the sellers bother to cost it correctly and don't just go flat rate box etc and n $ for filling in the form. Sadly ebay now prints everything out for them even the customs value. I like to try and save the £8 to £13 collection fee at this end and don't mind the vat.

John

-

The green grit wheels are a fairly hard bond and useless on other materials such as HSS and glaze quickly because it can't break the bond down. This is assuming it's a green grit wheel intended for use on carbide.

Of late I've put down failure to obtain a sharp edge on what ever it is comes down to wheel wobble. I have more than one grinders, one has no wobble. It's seems to be getting harder to get wobble free wheels that will dress easily. I mounted 2 recently on a grinder that locates them accurately. One's ok with a degree of run out that would be easy to dress out. The other far from it. I've not checked yet but the bore must be seriously out. I'm getting the impression that most companies prefer to sell junk.

In terms of brazed tip tools it will probably pay to buy of a company that does supply to professional users and has done for some time rather than being a pure tele sales type outfit that know diddley squat about what they are selling. I've come to that conclusion on indexed tips too. The brazed tip ones always used to have a grade stated - invariably cast iron grade. That's down to the grade of carbide and cutting angles.

On thing for sure if the edges are chipping on what is essentially a new lathe there is something very wrong with the tools. Most of these types of cutter should have angles suitable for interrupted cuts and should take way more HP than Brian can apply.

On sharpening in general if Hopper gets nice sharp HSS tools Brian should look very carefully at what he uses to do it with and the abrasives. The source is also likely to be useful.

John

-

Sounds like you might have one of their 4's. I think all of their lathes are listed here

**LINK**

I seem to have a charmed life drilling brass. I know it will grab so drill it's cautiously and take no notice of the noise it usually makes. Cautiously just means drill slowly. It takes very little effort at the feed.

Can't really comment on your parting off problem. A photo of the tool might help. To post that you need to create an album - the green album icon up the page, place the photo in it and then post it in a thread using the camera icon. Or put some where on the web and paste a link using the one next to the camera.

To post a shot the photo needs to be in the album before replying to a thread.

John

-

The only time I have had problems with them chipping and cutting badly is when I have ground too much clearance angle on them. It's best to keep that angle at around 7 degrees which means that the centre height has to be set with some care - over centre wouldn't be a good idea.

The other problem I had was on an ML7 chipping them and inserts but that was down to the lathe.

I don't have much of a problem getting a decent finish with a 60 grit green wheel but as I mentioned before I haven't used them for a long time now. It's mostly been on cast iron for tooling and parting off blades converted to screw cutting bits mainly for use on HSS.

Are you turning aluminium and it's sticking to the tool ? If so it's easy to flick it off with something - sharp knife. If you want to use carbide on aluminium you will probably be better off using inserts - some would say ground and uncoated ones but the more recent ones are uncoated and micropolished. It can melt and stick even then. The easiest way round that is to reduce speed. No coating may seem odd but aluminium oxide is pretty abrasive stuff and aluminium oxidises very quickly. Instantly is often mentioned.

If you honing them it's best to put the hone on a flat surface and feel the sides of the tool flat onto it and move along the cutting edge if you can as that way your unlikely to round off the cutting edge = fatal. A bit of thin oil makes them cut more efficiently.

John

-

Very probably no centre over that length and probably intelligent enough to try without one in if there was anyway.

The taper direction does matter but if it's in the wrong direction he needs more equipment than he probably has to find out just what the problem could be. I'm hoping it enlarges away from the chuck.

John

-

Sounds clear enough to me. Turned brass 3/8 dia by 30mm long and found he had a taper of 0.0025. Be better to keep the units the same. Either metric or imperial. An idea of the depth of cut would be good too.

First question - if you leave the same cut set and keep running the tool along several times does the taper reduce? Use slow feed.

John

-

Edited By John W1 on 12/10/2015 11:10:18

There is another "untouched" one that can be useful. Milliput. They don't give any physical characteristics.

**LINK**

I've found it can be moulded to a smooth shiny finish by using cling film as a "release agent". I used it to replace a toothed belt sector drive by moulding the teeth with the belt with cling film in between. Repairing stripped threads in plastic parts and all sorts of bits and pieces.

The epoxy putties sold in the £ shops also seems to work well.

John

-

CVA also did gearing for mod and dp but i don't have any details of how they did it. And a fancy screw cutting indicator for metric threads.

John

-

I've used one of the small electric ones jewellers watch repairers use for tool bits. They are pretty cheap on ebay.

John

-

There's a video of it in use here - the "noise" was down to not tightening the chuck fully.

**LINK**

John

-

No it can be ground and polished with the same gear as HSS.

It probably has the same characteristics as stellite. If heated and cooled quickly it will crack. Even dunking it in water while grinding a tool could have the same effect.

There is another similar alloy as well Tantung G.

Note the don't quench comment here. I understand they are happy to sell direct.

**LINK**

The root source of Tantung has been obscured by people searching for it. They are all stellites really. There is a bit of a run down here. There have been numerous grades of stellite in the past.

**LINK**

For home use I would suspect that speed feed and power may be a limitation as it's probably at it's best when the cutting edge is red hot which would help prevent chipping.

John

-

I do have the 127 - 100 so if I need to set a compound train might as well use it. This works out as follows but there will be other gear pairs that will do the same thing.

Newer machines seem to have switched to a 120 - 127 gear. I assume that's to get round the mesh problems.

John

-

Perhaps you should ask them how big a piece of depleted uranium you can machine on the lathe.

John

-

This is the one that I use more often. All but one of the gears come with the lathe. They use one as a spacer.

However people on the yahoo boxford group come along lusting after the 100/127 gear on the basis that it's more accurate even though lathe screw cutting is not that accurate really anyway.

John

-

This is about as far as I have gone, tending to overdrive the gearbox as the fine feed is so low with the normal gearing.

Still some compounds to get rid of and I suspect I am gear short to do that but can hit 0.35mm to 3/4um. I haven't checked if the compounds will mesh. As far as I know all are with standard boxford gears. They came with the lathe when I bought it.

The basic gearbox drive is 20 - 56 and setting as per this

i hadn't thought about using the feed ratio as that uses the rack to move the saddle so wouldn't be so accurate. It works out at about 2.9 : 1 compared with the lead screw feed.

I recently downloaded the find the gears application from lathes co but haven't set it up yet. I did these iteratively on paper Tedious.

John

-

Edited By John W1 on 10/10/2015 11:12:56

Has anyone come up with some magic gears for a Boxford with gearbox ? I can post as far as I have got if anyone is interested.

John

-

As they supply a bigger 4 jaw the comment doesn't make much sense really. I only mentioned Boxford because it's right by me so I could measure it. I just don't believe an extra kilo or so would make any difference. I could understand why people wont do what I am about to do fit a 200mm 3 jaw. The weight difference in that case is very large. I'm doing it to obtain a bigger hole in the chuck not to hold bigger work,

Noticing another comment, chucks shouldn't be used with the jaws sticking out really and I'd guess some people do take a bit more care if they have to use them like that. To far out and the scroll and teeth on the back of the jaws wont all be meshed and there is far more chance of striping the scroll.

I can't weight to hear the answer.

John

-

Yes the cutting tool angles. The form on the worm will be the same as a rack meant to mesh with the gear.

The helix angle needs to be in a pretty precise relationship to the angle the worm is at when meshed with the gear. That's why I suggested making the worm angle adjustable. It could be locked once the mesh is set correctly.

John

-

There are a couple of programs on lathes co uk where the available gears tooth counts are entered along with the pitch required and it will find the closest approximation. One for lathes with a gearbox and one for those without.

I find this chart useful at times

John

-