Axminster 1628VS lathe head and tail stock alignment.

[Democritus]

Hi
I’m new to this forum, so hello to everyone.
I have owned an Axminster 1628VS lathe for the last 2 and a bit years. I am a relatively inexperienced woodturner, and up to recently have concentrated on developing my skills on bowls, platters, boxes and the like. The lathe has been great for these projects. Recently I decided to have a go at pen making, and have managed to make some reasonable ball pens. I have a problem with the lathe, however, in that when a pen blank, marked with centres, is mounted in my chuck for drilling, the drill bit in my Jacobs chuck will not centre on the blank, being about 1mm off centre. This means that any holes drilled through the blank are off centre, resulting in uneven walls when the blank is turned to bushes. I have tried testing the alignment with a dead centre in the head stock and a live centre in the tail stock, and when these are brought together they align ok until the tailstock is locked in position, when, again the points are out by about 1mm.
I wonder if anyone else has had a similar problem with this lathe, and if there is an easy solution. Someone I know suggested that adjusting the leg anchors might twist the lathe bed to correct this, but I don’t want to mess with these if there is another solution.
Hope someone can help.

 

[CHJ]

Really need to determine where the error is being generated.

1. If you clamp a substantial (straight) steel bar in your chuck, does it eyeball in alignment with the bed ways, and if you move the head does this alter?
2. With tailstock quill retracted does the centre point align with the headstock centre when clamped?
3. If you extend the tailstock quill fully out does its alignment with the headstock centre differ?

 

[nev]

Any lathe issues aside, rarely will you drill any substantial length without the drill bit deviating in the wood slightly, either following the grain or just a flex in the drill bit. Which shouldn't be an issue as once drilled the blank can be placed between centres on bushings or on a mandrel and therefore does not require the hole to be perfectly central in the blank because your centre will be the 'hole' and you will remove the wood around it to match.

 

[Steliz]

Have you checked the head and tail stock cam locks for debris?

 

[Democritus]

Thanks, guys.
I’ll check all the things you suggest, and let you know what happens.

 

[Robbo3]

There is a slight amount of sideways movement on the tailstock alignment - there has to be some otherwise it would be too tight to move. But it's enough to allow the misalignment.
With the headstock in line with the bed bring up the tailstock & see where it needs to be positioned to get the drive points to line up. Then remember this position for next time.
I also get in the habit of making a centre dimple in everything that's held in the chuck so that it's easy to centre again if needed. A dimple would allow you to line up the drill bit so that it starts centrally.

 

[Phil Pascoe]

You don't say whether the error is horizontal or vertical. I suspect horizontal, but just to be sure.

 

[Lons]

Hi
That your drill bit is 1 mm out should make no difference providing your pen blank has sufficient thickness, doesn't even matter if it's off centre at the exit end as long as there's enough left to turn down to size.

I'd suspect you have a different issue. e.g.
Assuming your drilled hole is accurate, your pen tube is correctly glued in and your bushes a tight fit to the tube then the walls of the turned pen will be accurate, unless...... your mandrel is bent or flexing possibly by you using too much pressure or blunt tools/poor techniques. Some timbers can also have soft spots and can cut or sand away unevenly if you'r not careful.
A tip some use including me occasionally is to turn the blank 90 deg in relation to the bushes when almost finished at final sanding. One other point it that bushes are consumable as aggressive sanding wears them down so need to be replaced occasionally or make you own it's easy enough to do that or turn the pen blank between centres.

If you have a chuck then pen jaws make drilling easier which is my preferred method even though I have a decent pillar drill which others prefer and if you're into pens maybe check out http://www.penturners.co.uk/ where like on here you'll get a lot of help.

cheers
Bob

edit: Just another thought, you do square off the ends of the plank with the tube using a barrel trimmer or sanding disk don't you?

 

[Dalboy]

After checking the points already mentioned if you find that it is only the drill bit that is slightly off centre the problem may be a combination of a couple of things. Chucks for drilling may not always hold a drill bit exactly central, the drill may have a very slight bend in it. One thing I find helps over come the grain problem when starting a hole as mentioned above is to use a centre drill first then replace with the bit of the correct size.

 

[J-G]

After checking the points already mentioned if you find that it is only the drill bit that is slightly off centre the problem may be a combination of a couple of things. Chucks for drilling may not always hold a drill bit exactly central, the drill may have a very slight bend in it. One thing I find helps over come the grain problem when starting a hole as mentioned above is to use a centre drill first then replace with the bit of the correct size.

That scenario would be the very worst of all worlds Dalboy! If the drill bit itself is 'bent' - even by a ¼mm, then it will cut oversize - a 7mm drill that is bent 1mm will start the hole at 9mm - there may be some tapering as the hole gets deeper and other 'forces' conspire to minimize the deflection but you'll never drill a parallel hole. and that will cause all manner of issues when fitting the pen tubes.

The 'Use a Centre Drill' tip is excellent - I always work that way.

 

[Dalboy]

The 'Use a Centre Drill' tip is excellent - I always work that way.

It may take a little longer but I find it a benefit especially when I am making the wooden models that I am currently doing. I have even resorted to using milling cutters in the pillar drill to cut slots in small pieces of wood where a router is just too large.

 

[Democritus]

Hi Guys,
I’ve checked the things you suggested. The lathe bed/iron rod eyeball as straight, the deviation remains at any distance/ extension of the quill, and there doesn’t appear to be any debris.
I’m going to try uploading a couple of photos to show the problem.

 

[Democritus]

Here’s another one

 

[CHJ]

The lathe bed/iron rod eyeball as straight, .

Good.

the deviation remains at any distance/ extension of the quill,
.

OK this proves that the longitudinal axis of the quill is in line and parallel to the headstock centre line, Good.
What it confirms is that the tailstock is not centred on the lathe bed (back to front) when clamped. Annoying.

On a decent metal lathe there would be an adjustment for this to eliminate any machining errors, can you investigate the base of the tailstock to see if it, or its clamping components can be adjusted or dressed to offset the tailstock in the corrective direction when clamped.

 

[selectortone]

I have the same lathe. There is a small amount of play in the headstock when not clamped for the reason previously stated - there needs to be some slack to allow it to move up and down the bed.

The headstock and tailstock can be aligned if necessary with the alignment tool supplied. I've got used to mine now and can jiggle it by hand and eye to where it lines up pretty much exactly. For many jobs on a wood turning lathe it isn't essential for them to line up extremely precisely anyway. It's more of an OCD thing.

As far as boring pen barrels, you will be very lucky not to get some deflection for reasons also already stated - flexibility of the bit and tendency to follow the grain. I have never found this to be a problem as (again already stated) the hole you drill becomes the centre line and provided you have left enough material on the blank you will turn it to true anyway.

 

[Democritus]

Thanks, guys
The tailstock is clamped by a simple cam device pulling a large washer up against the lathe bed rails. The doesn’t seem to be any mechanism for adjusting it. There is a large locknut that I suppose is there just to hold the washer when the tailstock is unclamped.
I tried putting a shim under the tailstock, but it didn’t seem to make any difference. I’ve used an alignment tool between the headstock and tailstock, but when it is removed, the problem with the tailstock returns. Both headstock and tailstock are 2MT, but I think there is a bit of play at the tailstock when a live centre is put in, and certainly as the quill is advanced.
I’m intrigued by the idea that it doesn’t matter if the drilled hole is slightly off centre in the pen blank, as turning it will produce even thickness walls anyway. I ‘ll give that a try.
Thanks very much for your help and advice. It’s much appreciated.
If anyone has any further ideas...
Best wishes
D.

 

[CHJ]

Although a 'Niggle' ; as others have pointed out not a major problem for such things as pen blanks which will be re-centred anyway.

It may cause a discrepancy if you ever try to drill an accurate diameter hole in a chuck mounted piece
by causing it to cut oversize especially with something such as a stiff Forstner bit.

 

[Lons]

I’m intrigued by the idea that it doesn’t matter if the drilled hole is slightly off centre in the pen blank, as turning it will produce even thickness walls anyway.

just to simplify that, say you have a 20mm square blank and are making a slimline with 7mm tubes assuming your drilled hole is dead centre all the way through you have 6.5mm to play with all round, in most cases unless turning a fat in the centre pen that's way more than enough. If you drill and the exit hole is 3mm off centre you still have a minimum 3mm thick at the narrow point so still more than enough. finished wall thickness at the fittings ends will only be a mm or so.
I like slimlines to be thin so often use 15 / 16mm blanks but have regularly turned 12mm corian by drilling carefully easier to keep the drill straight of course as no grain to contend with.

I mentioned squaring off the ends before turning as that's important because the bushes need to sit flat and square to the tubes.

If you're bending the mandrel, try turning one tubed blank at a time or turning the blank around. It's not impossible of course that you have a poorly machined mandrel but you can check the runout on that and your headstock with a dial gauge if you have or can borrow one.

I have 2 lathes btw, a little Jet and the smallerbrother to yours a 1416vs

 

[Democritus]

Hi Chad and Lon
Thanks for your help.
I suppose i’ll have to work round this problem. I do use a trimmer tool to square the ends of blanks/tubes. My mandrel came with a Rotor kit I bought, and I have a tail stock mounted mandrel support. I don’t think the mandrel is bent.
I also (in response to the alignment problem) bought a pen blank drilling vice from Turners Retreat, but that has raised its own problem. I use it on my Record drill press, and it’s great for smaller drill bits. The problems begin when using larger (and therefore longer) bits. The distance between drill chuck and vice is too small , even with the primary table turned away. The column on the press is 13 inches. If i am going to be able to use the vice, i’ll need to get a taller press....
If anyone is thinking of getting a pen blank drilling vice, make sure your drill press is big enough.

Thanks again
D

 

[J-G]

...I’m intrigued by the idea that it doesn’t matter if the drilled hole is slightly off centre in the pen blank, as turning it will produce even thickness walls anyway. I ‘ll give that a try.

If you are intrigued by that, perhaps you are also thinking of holding the mandrill in the chuck and not supporting the free end with the tail-stock. That would give rise to potentially uneven wall thickness.

I would never consider making pens except 'between centres' - that means a dead centre in the head-stock and a live centre in the tail-stock. It then becomes very obvious that the wall thickness must become even. It actually doesn't matter if the head and tail-stock are a tad out of alignment --- it would if you were using a metal working lathe with the tool in a saddle since you would then cut a taper, but for wood turning, by hand, those considerations all go away.