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Member postings for old mart

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

Thread: Where has my post gone?
20/06/2019 20:31:51

I have just wasted 3/4 of an hour creating a new thread and started adding photos when the whole lot disappeared. Any ideas where it went?

Thread: How have Apple found out my new Debit Card number?
19/06/2019 22:41:09

Did they have your bank account details for a direct debit?

Thread: Changing Tapers on an Arrand boring head.
19/06/2019 22:37:04

Does your MT2 arbor have a male 1.5" X 18 thread? That size seems to be a standard for smaller boring heads. Arceurotrade sell replacement arbors with that thread. If so, the MT3 one could be replaced if you have to destroy it.

If there is a flange on the arbor where it screws into the boring head, a couple of flats could be milled in the flange to hold it securely in a vise. Then more torque could be applied to the head.

Thread: What are these wheels /tyres?
19/06/2019 22:12:58

I like the way the cockpit cutouts have been made into the mudguards.

Thread: 8BA to 1/8 Whitworth
19/06/2019 22:06:35

The 8BA is 0.086" od and the tapping size for 3/32"W is 0.070", it will end in tears. 1/8"W would be ok, as the tapping size is more than the od of 8BA @ 0.0984". 

Is there room to drill and tap to a larger size, and Loctite in a plug to d&t to 3/32W?

Edited By old mart on 19/06/2019 22:09:02

Thread: Aluminium cylinder blocks
19/06/2019 21:51:34

Get the bores hard anodised and ground, probably a costly option but better than chrome which would also have to be ground.

Thread: Lathe Speed - What am I missing out on?
19/06/2019 21:39:02

Sometimes just changing the speed a little will improve the cutting, reduce chatter or change the surface finish.

My car has a six speed box, I don't stay in third all the time.

 With carbide inserts, you have to take deep cuts with inserts designed for steel or the surface finish suffers. Using inserts designed for aluminium to finish steel allows very small depth of cut, useful when you are creeping up on the required size. They are sharp like hss.

Edited By old mart on 19/06/2019 21:44:54

Thread: Is this cheap type of VFD worth buying?
19/06/2019 21:08:15

I found the site www. inverter and was amazed at the sheer number of VFDs' they sell.

Picking one in the power range I was interested in I noticed a downloadable pdf with the installation and setting up instructions. It was amazingly comprehensive, even including details of how to wire a complete remote set of standard on off buttons, emergency stop and speed controlling potentiometer. I had been concerned about running a machine with only those rather small controls they have on the VFD box.

Thread: ABRA File or Modern equivalent ?
19/06/2019 20:48:08

The tension type of Abrafile is not the original concept at all, back in 1959, at school we all were given an Abrafile which was about 1/16" diameter by 2" long in a little black wooden handle about 5/16" diameter by 1 1/2" long. Their main advantage over ordinary files was that they were bendy. I still have a few short bits and a 1/4" version with a plastic handle. I also have some of the tension versions.

Thread: Is this cheap type of VFD worth buying?
18/06/2019 17:39:06

I am thinking about using one of these VFD inverters to control a 3 phase 6 pole 3/4 hp electric motor. The motor runs at 900rpm and halving that would be useful. I have access to both single and three phase power.

The ebay listing on the UK site is : 223486597368.

Thread: Improving runout in a slitting saw
17/06/2019 21:19:42

Maybe thinking about an adjustable mandrel would be the better option. All of mine are eccentric too, probably not being British made is the reason.

Thread: Start of Tom Senior refurbishment.
17/06/2019 20:19:41

I've made a little progress on the antibacklash for the X axis. I made a sleeve to be loctited into one of the bores in the cross slide with a 3/4" clearance hole for the leadscrew. Drilling 3/4" wasn't enough, I had to bore it out a few thou to give clearance. The end for the nut was turned down to just clear the casting and bored to about 1.2" diameter by 1 3/8" deep. I turned the nut down on a mandrel for concentricity, and ended up sizing the pair for a super fine thread. I chose 40tpi and started the female thread by undercutting the bottom 1/4" of the hole and used a left hand threading tool which I had made out of Densimet, spindle in reverse and cutting away from the chuck. The finest er16 inserts I had were 0.5mm, or 28UNF. I went for the 28, as the thread was a 1 off and cut 0.012" deep in 0.002" steps, then 0.001" steps, with a spring cut at the end.

The male was done using the same insert, and I started trying the fit when I got to 0.011" deep. The fit ended with about 0.001" clearance and a total of 1" length of thread contact. The end of the nut projecting from the sleeve got turned down, leaving a step for a locking collar held by two 4mm screws. I will use Loctite 628 on the sleeve- casting joint.

Thread: Threading Problems on Colchester Student
17/06/2019 16:20:03

When cutting metric threads, I would always use the same number on the thread dial.

17/06/2019 15:13:26

The Smart & Brown model A that I use does imperial and metric threads, I have a 120/127 compound gear for it. I cannot understand why there is any difference between imperial and metric threading, and anyone who cannot read a thread dial shouldn't be using a lathe in the first place.

17/06/2019 13:53:45

The S & B also has a single element half nut with a bronze slipper on the other side of the leadscrew. I am always careful engaging the leadscrew nut fully as it can drive the saddle even if not aligned., This happens frequently when using the leadscrew for ordinary turning and doesn't matter in that application. If fully engaged, it has never slipped out of drive, even before making the new nut.

I disengage the leadscrew nut at the end of each pass, withdraw the threading tool and run the saddle back by hand, leaving the spindle running and not reversing. This is easier for me than reversing and withdrawing the tool simultaneously.

Thread: Limitation of a milling machine with low spindle RPM.
17/06/2019 13:34:05

The higher speed would be an advantage especially if using small solid carbide cutters. Reducing the feed rate would make up for the lack of speed if need be.

I am facing the opposite problem, The Tom Senior light vertical which I am working on has only 4 speeds, the slowest of which is over 500rpm. A bit fast for larger drills and cutters in steel.

Thread: spindle bearings
17/06/2019 13:12:51

If modifications to the spindle are required, then the use of another lathe big enough to do the job is required.

As Ketan advises, the original type of bearings would be good candidates, especially as the original bearings had a long life.

Thread: Cheap Carbide Lathe Tools
17/06/2019 13:05:06

Proper carbide inserts have sophisticated tip geometry which hss and brazed carbide cannot match. Only first generation inserts such as TPUN lack the advantages of modern types.

Thread: Threading Problems on Colchester Student
17/06/2019 12:49:34

The Smart & Brown model A that I use has a new leadscrew nut and no endfloat in the leadscrew, but I wouldn't dream of leaving it in gear when reversing. Why? Because there is backlash between the spindle and the leadscrew through the gears.

Its easy to check, just set up for threading, turn the chuck by hand until the saddle moves and then turn the chuck the other way. See how far the chuck can be turned before the saddle starts to move. Using a dti will give the most accurate results. The finer the thread pitch set, the greater the backlash errors will be.

Edited By old mart on 17/06/2019 12:51:36

Thread: spindle bearings
16/06/2019 13:58:50

I had to replace the bottom taper roller bearing for an R8 mill spindle, the wait was a week for SKF, so I chanced it and bought Chinese, and it has been running fine for 5 years.

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