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Member postings for Pete Rimmer

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

Thread: Belt Driven Hacksaws -
22/08/2018 21:55:56

Remove the motor pulley and turn the shaft so the keyway is not pointing towards the big pulley. Place a straight edge across the edges of the big pulley so that it extends up to the motor shaft. Put a small square on the straight edge and check if the motor shaft is truly perpendicular to the straight edge, which will make it parallel to the big pulley axis. If it isn't, loosen the motor and adjust it until it is. If the pulleys are now aligned and parallel, the belt will run true.

Once you have the motor pulley parallel to the big pulley use a marker pen to draw marks on the base along the motor feet. Then if you have to adjust the motor to tension the belt you have a visual reference to keep the shafts aligned, you just eyeball the gap from the line to the motor foot.

Thread: Lathe bearing oiler wicks/felt
16/08/2018 21:13:31

I fitted new felt wicks into a 100yr old Cataract lathe yesterday. I used 5mm round F1 felt. I see that there's a guy selling 1/4" diameter for £15 a metre. If you need it flat just flatten it out in some smooth-jawed grips/pliers. Mine needed to be flat one end and round the other where it dipped into the reservoir.

Thread: Facing Error
16/08/2018 19:25:07
Posted by SillyOldDuffer on 16/08/2018 19:08:37:
Posted by Pete Rimmer on 16/08/2018 18:18:24:
Posted by XD 351 on 16/08/2018 10:37:56:

If you can confirm that the bed is not twisted , the headstock is aligned correctly it only leaves one thing - the cross slide is not perpendicular to the spindle .

Therein lies the conundrum. If the cross-slide is not perpendicular you would still not see any dial movement by following the cutter's path with a dial gauge, which it seems is what's happening.

...

Confusion earlier about this point. True the DTI follows the tool-path BUT it was positioned on the opposite side of the plate to that cut by the tool. In that position the DTI sees the hill caused by the taper and registers twice the error. When positioned on the other side, the DTI parallels the tool-path and all appears well.

Dave

Ah, then the error is doubled as I'm sure someone mentioned previously.

Where are you Dave if you're close to North Kent I could pop by and assess it for you?

16/08/2018 18:18:24
Posted by XD 351 on 16/08/2018 10:37:56:

If you can confirm that the bed is not twisted , the headstock is aligned correctly it only leaves one thing - the cross slide is not perpendicular to the spindle .

Therein lies the conundrum. If the cross-slide is not perpendicular you would still not see any dial movement by following the cutter's path with a dial gauge, which it seems is what's happening.

What it could be is that the slide or gib is worn or such a poor fit that cutting forces are deflecting the cross-slide where dial gauge plunger is not.

15/08/2018 18:01:03
Posted by Keith Rogers 2 on 15/08/2018 17:15:03:

My bet's still on headstock misalignment thinking.

Keith.

It's very possible but you have to make the presumption that someone with the presence of mind to measure for concavity in a face would also have checked for taper in their normal turning, especially if it's to such an extent.

The only thing to do is ask SOD:

Dave, have you checked that parts you turn which are held normally in the chuck for taper? If not, that is the very next thing you should do.

It does have the minor complication that a tapered part might be the result of a twisted bed whereas a faced part would be barely affected by bed twist if at all.

12/08/2018 18:12:57

If you swept the face by mounting the dial gauge on the same cross-slide that you used to face the part with the tool, you should see no movement regardless of whether it's face is truly flat or not.. Since you do it points to a worn or maladjusted cross-slide.

Thread: Cleaning Lathe after use
08/08/2018 19:55:47

I use magnets for collecting swarf in the tray of my hobber. I t stops th fine stuff from clogging up the oil pump thought I've just bought some paint filters to use when hobbing cast iron.

The only big drawback from using magnets is that they tend to magnetise all your tools, which in turn causes the swarf to stick to them and that gets very annoying. I have to have de-magnetising sessions every now and again.

08/08/2018 19:00:02

A good shop vac is one of those essential tools IMO.

To clean up after turning cast iron I use a Numatic shop vac followed by washing down with brake cleaner in a pressure pot. The pots are 16 quid and 4 gallons of brake cleaner about £36 on offer. You can see it wash the finest particles away. you could use a trigger gun in a pinch but they don't last 5 minutes with brake cleaner in them.

After that re-lube with way oil.

Thread: Gear Hobber : Design ideas please ...
07/08/2018 17:30:09

I've got a hobber Michael. If you want to knock out the blanks I could cut the teeth, or if you're near North Kent you could come and cut them yourself.

Have to check that I have a .8mod cutter first though...

Thread: Milling Table "fault"
03/08/2018 19:01:58
Posted by Tony Pratt 1 on 03/08/2018 17:57:33:

If you are traversing the y axis under an indicator the column being 'out' or not will make no difference.

Tony

Tony you're quite right, I had a senior moment there. I'll blame it on the heat, or the hard day at work etc.

03/08/2018 16:54:57

It's far more likely to be the column that's out of perpendicular to the y-axis ways. Does the column bolt to the base?

Thread: 3-Phase Motor Conversions: Are They All Hype?
31/07/2018 07:00:54
Posted by Neil Lickfold on 30/07/2018 18:19:44:

After setting the motor to the lower voltage option, get the hand book that came with it, and check the current settings, for your motor. From the motor data plate. The drive will generally go from 20hz to 50hz, but is programmable to 400 hz. Don't go over 70hz on the max limit. Some say don't go over 60z,(USA and Canada power frequency). Like others have said, as the frequency drops,so does the RPM, and so does the total power available. Also there is breaking options, and slow down/ decelleration settings. I think mine is like 0.3seconds or something like that, and have the accelleration at the same rate, on the motor start up and shut down.

I am surprised that if you brought the unit as a complete set up ready to run, that they would have the motor not in the correct configuration. I am assuming that your VFD is the 220V 3phase output one, and Not the 415V output one.

I have a microswitch inline on the S1 control circuit. This micro switch I use is a normal closed one, and is opened/broken circuit when the contact is made. It stops the lathe for when I do forward thread cutting. And allows me to turn the switch to reverse to wind back for another threading pass. Really good for internal threads. I have some pictures in my Album with it.

Neil

What's your reasoning for not exceeding 70hz on the drive Neil? Most lathes have 4-pole motors which will happily run at the speed of a 2-pole.

Thread: Thread cutting with carbide inserts
28/07/2018 23:15:38

There's no compulsion to use carbide at high speed if the circumstances prevent it. Thread as slow as you like, but beware you might suffer broken edges on the tip of the insert especially if you stop the spindle with the tool in the cut or don't have a groove to run into. I've been cutting 1.5mm threads today at 200rpm with a hand-ground carbide tool (ground from a busted end mill) and I've had to re-grind it several times after breaking the edge. HSS wouldn't stand up to it at any speed in this material. The task doesn't allow for a groove so I've been manually retracting the cross-slide and a couple of times I've missed-timed it then off came the tip.

Thread: Mellor lathe
28/07/2018 18:15:46

Howard makes a good point, especially for older lathes now fitted with quick change tool posts. Lathes which originally would have had a lantern toolpost hold the tool on or very near the compound's swivel centre-line so a travelling steady would would be designed to sit just to the left of centre. 4-way toolposts and more recently quick change tool posts have much more width and hold the tool much further to the left, in a position which is likely to clash with the steady.

I've had to fabricate a steel travelling steady for one of my lathes for which I have the original item because of how awkward it was to use when making leadscrews.

Thread: Hi Guys-need help!
28/07/2018 07:39:15

Hi David,

The threaded stud on the end of the capacitor canister is simply there for mounting purposes.

When you remove the cover from the terminal box you'll see the two power connection, which you have already identified, and the earth connection which is typically a tapped hole in the casing usually in one corner of the enclosure under the lid. There should be an 'earth' sign cast in the surface right next to the hole. If the motor is really unused there's a high probability it will also have the screw in it.

Thread: 2 start thread
22/07/2018 20:27:55
Posted by Simon Williams 3 on 22/07/2018 14:38:15:

Hello all, cor ain't it 'ot!

I have recently found myself repairing an exhibition stand, where the flat panels have 16 mm rods each sides to hold them together. I discovered that the thread I thought was M8 in each rod was actually 8 mm OD, but was two start. So the thread pitch is actually 2.5 mm not 1.25 mm.

Which led me to wonder how such things are specified. The thread pitch measured with a thread gauge is 1.25 mm, but would I be right in supposing that, if I needed to specify such a thing to a professional turner I ought to call it "M8 x 2.5 pitch 2 start" (assumed symmetrical)?

Look forward to hearing what the forum thinks?

Thanks as always, Simon

You're nearly right. The pitch is still 1.25mm, but the LEAD is 2.5mm If you specify 'Thread 8mm, 2.5mm pitch, 2-start you'll' either get a 5mm lead thread or (more likely) an irate phonecall asking what it is you really want.

So ask for 'Thread, 8mm OD, 2.5mm lead, 2-start'

Thread: Bantam lathe chuck
22/07/2018 16:52:42

Pull the jaws out of the chuck. Set the chuck so that one jaw slot is perfectly horizontal (at the back or the front) and run a tenth-reading DTI along the jaw guide (with the mag mount set on the cross slide). If the dial reading goes up or down rotate the chuck 180 degrees so the slot is now pointing the opposite way and repeat the test using the slide on the same range of travel i.e. don't wind the cross-slide to the other end, re-position the mag mount.

If you get anything but the same reading with the jaw slot at the front and the rear, your chuck is fubar.

21/07/2018 18:59:34

I bought a lathe (also a Bantam, ironically) which had a Pratt Burnerd chuck that produced variable runout in the part between about 8 and 15 thou. The jaws were a good fit in the slots, didn't appear worn and there was nothing obviously 'wrong' with the chuck except that it had runout.

Turned out that the chuck was slightly bell-mouthed. Gently holding a part in the jaws meant that you could rock it around as it was only held on the very back of the jaws. The jaws were perfect, it was the body of the chuck that was deformed. This was a 4-1/2 inch Pratt Burnerd integral camlock chuck so a good quality item, I guess that sometime in the past someone must have really wrenched down on a part held at the end of the jaws or maybe had some other even where the part was torn out, permanently damaging the chuck body..

Soon after I bought a tidy 5" PB chuck that only had outside jaws so I tried the jaws from the bent 4-1/2" chuck in the 5" one and they consistently gave better than 3 thou runout on both the inside and outside sets.

The main point of the story is that it's common to immediately suspect worn jaws or a worn scroll and often the attempted 'cure' is to grind the jaws but don't jump to this conclusion too quickly - hardened steel jaws are tough and slow to wear, iron chuck bodies not so much so do your investigations before grinding parts that might have nothing wrong with them.

Thread: Should every machine tool be bolted to a concrete floor?
19/07/2018 20:47:59

If you have a lathe like a Bantam with a pedestal each end firmly bolted to the bed then you should both level (align, actually) and fix the lathe down to eliminate bed twist because it takes no effort at all to twist the bed if it's set on any kind of uneven floor (even floated concrete floor isn't flat).

Currently I'm refurbishing a South Bend lathe which is the old design of headstock base casting and tailstock legs, this absolutely must be levelled and fixed if it's to work as intended and keep doing so.

Thread: Milling table regrind
09/07/2018 17:47:56
Posted by Pete on 09/07/2018 13:06:11:

Even a brand new top of the line mill will have a few thou of clearance. It has to or the table couldn't move.

A few tenths, but not a few thou. You wouldn't even start scraping a few thou of wear unless you had no choice at all, you'd mill or grind it first then scrape it once you were closer than a thou or even half.

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