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Member postings for DC31k

Here is a list of all the postings DC31k has made in our forums. Click on a thread name to jump to the thread.

Thread: Can one buy pliers with parallel jaws that lock like mol
06/05/2021 07:34:50

There are very subtle distinctions in the mechanisms above. Some have parallel jaws; some have parallel action; one (the original photo) has, for want of a better term, perpendicular approach.

With parallel jaws, at any one point (i.e. when they are gripped onto the object), the jaws are parallel. As they move towards this point, the jaws may not move perpendicular to each other. All the ones above have this function.

With parallel action, the jaws stay parallel to each other while they are moving. The first one in the original post and the Stahlwille one have this function, as does anything with pivoting jaws.

With perpendicular approach, the jaws do not translate laterally as they close (so they are just like a vise). Only the first one does this.

Please consider the possibilities of these:

https://www.toolsntoolsuk.co.uk/shop/140-mm-side-screw-parallel-action-flat-nose-nylon-jaws-pliers-jewelry-extra-jaws/

The adjustment screw on them means that the distance between the ends of the handles can always be the same no matter what thickness they are gripping. You would have to make a locking device, but that can be as simple as a loop of metal, similar to that used by blacksmiths for a tong lock.

05/05/2021 18:34:57

Please see if any of these come close to your requirements. The last one in the list is stretching the specification a little.

https://www.toolsntoolsuk.co.uk/shop/parallel-action-locking-pliers-jewelry-craft-hand-vise-smooth-flat-brass-jaws-6/

https://www.misterworker.com/en-gb/stahlwille/parallel-jaw-self-grip-wrench-6562/8994.html

https://www.tooltique.co.uk/shop/vintage-speetog-parallel-jaw-adjustable-locking-plier-clamp-good-condition/

https://www.riogrande.com/product/swanstrom-self-locking-parallel-action-pliers/111649

https://www.cromwell.co.uk/shop/hand-tools/locking-pliers-and-grips/255mm-10inch-parallel-plus-grip-wrench/p/KEN5587250K

Thread: The TurboCAD Problem - A Further Question
05/05/2021 11:30:00

I do not know if TC has a 'purge' or 'purge all' command similar to AutoCAD, but using that could help if it does.

Thread: Digitising software
05/05/2021 09:55:30

Pending a better answer, what follows will do what you want.

Any CAD program will allow you to import a scanned .JPG file and use it as an underlay to the drawing.

It will also allow you to draw two orthogonal axes and rotate the scan until it coincides with these. This helps to correct any skew in the scan. Move the corrected scan around in the drawing until the coordinates of the scan axes match the drawing coordinates.

Draw a series of 'point' entities on the curve. Export the drawing as an ASCII dxf file and open in notepad. The coordinates for the point entities will be easily identifiable. Strip away all extraneous things in the file, just leaving X, Y pairs. Import these as .CSV into the spreadsheet.

Thread: Harrison L5A tool post mod
04/05/2021 09:08:53

Remove the rusty half nut and the full nut below it. The cone will then come off, leaving the stud screwed into the T-nut in the slide. Remove T-nut and stud, leaving bare top slide casting. This is your starting point.

Make new T-nut, stud and centring bush if required to suit chosen QC toolpost. If the dimensions suit, you can make the upper thread on the stud the same as you already have so you can reuse the clamping handle.

If you want to seamlessly swap between the current one and a QCTP, you need to make a quick change toolpost post.

Thread: Protective film for polished metal.
04/05/2021 08:02:47

The generic search term is 'low tack protection film'. A small roll is available from Toolstation, product code 20527.

Thread: Lever scroll chuck with one hole set
03/05/2021 07:29:44

Is there any utility in removing the chuck from the machine first and then submerging in a bucket of something penetrating?

The turning the stock from the jaws is a very good plan as then it does not matter which way you turn it - you just need to induce some movement in the chuck scroll.

Extreme, desperate measure might be hot caustic soda: not only will it dissolve the aluminium stock, but it will help with internal gumming up.

Thread: Mt3 extension for tailstock
02/05/2021 08:24:21

If you are worried about droop or wobble, and if space permits, you can always snug the fixed steady fingers onto the extension.

Thread: Workshop and Drilling holes with an ER collet chuck
02/05/2021 08:21:56

And a third way, headroom permitting, is to use a drill chuck on a straight arbor and hold that in an ER collet.

This way, you have the quick change facility of the drill chuck without having to change a collet for each bit size and without needing three hands to hold the 5.5mm drill bit in the 6-5mm collet, turn the ER spanner and hold the spindle brake. It is bulky if you use a 1/2" capacity chuck, but for a 3/8" or smaller, it works well.

For lightning quick change, buy a spare ER nut, and collet to suit the drill arbor. Make a shallow groove at the top of the arbor. Assemble nut, collet and arbor and put O-ring on groove. When needed, just unscrew ER nut with its collet and screw on complete drill chuck assembly.

While you are drilling the hole, use the other hand to remove the collet from the ER nut and pre-load the next collet required for the following milling cutter.

Thread: Looking for DRO system with an output pulse on zero
01/05/2021 15:06:16
Posted by Clive Foster on 01/05/2021 13:13:31:

I do wonder just how difficult it would be to intercept the display driver for the usual inexpensive import DRO box and interrogate that to find all zeros so the power feed can be stopped.

But even if you did that, it will not mimic a fixed mechanical stop or a manually-controlled stop on a DRO zero. And it is that part of it, I do not think you yet appreciate.

Just switching off the power feed will stop at an indeterminate and unrepeatable position. Just think what might influence it: cutting load, slide friction, speed it is going when you switch it off.

Under the hood in Mach, etc. there is a lot of maths going on before the soft limit switch or zero count is reached. It looks ahead and takes action because it knows how far away it is and what it is doing on the approach to it. The stop comes as no surprise.

In a similar way, it is why you would always rehome the machine after you hit a hard limit (or the big red button). For that situation, the stop signal comes as a complete surprise to the machine. It does all it can to stop as fast as possible but the actual position in which is eventually comes to a halt is indeterminate.

01/05/2021 11:37:46

As you say, Mach 3 and LinuuCNC have the capacity to do what you want. Both ot them will have an internal variable in the stlye of CURRENT_X_AXIS_VALUE. You would have to write a macro that runs continually and compares that value to your required one and then dives off into an interrupt routine that rings the bell when the values become sufficiently close (not necessarily 'equal' ).

To do this in principle in either program is not difficult, but it is the time and effort spent learning how to do it that will weary you.

Someone has posted here an Arduino sketch that does a DRO summing (quill and knee). It would be possible to use that as a building block for what you want. You can intercept the signals from the scale, let the relevant part of that program decode them and them perform the routine described above for Mach. You would need to give it both the current value and the desired value so it can do its work.

The main thrust of this is to suggest you do some trials on the human-machine interaction aspect of your idea before going much further. Stopping something moving on the sound of a buzzer (triggered by your pulse) is not repeatable. What you do at the moment is to look at the DRO display, see how close it is to zero and how fast it is changing and adjust your handle turning to suit.

Rig up a dial indicator and a microswitch-triggered buzzer on the machine. Set the bzzer to sound when the indicator is at zero. Now cover the indicator and drive into the microswitch. See how close to zero you get. Repeat nine more times.

An analogue dial with a moving hand (or its on-screen equivalent) or even watching the numbers of a digital display count down will help you a lot more than a single tone.

Think of it in reverse: starting an athletics race or the Christmas tree at a drag race. The best athlete is the one who goes on the 'B' of the bang, not the 'G'. The winning car is the one that takes off as the lights start to dim, not when they are fully extinguished.

If you want to take the quadrophenia route, then the parking sensors on a modern vehicle might be a good model. The programming is not trivial as it has to take into account not only distance but speed and acceleration. It would be interesting to experiment to see if you can stop your car the same distance from the brick wall every time, just using the onset of the continuous tone to guide you.

Edited By DC31k on 01/05/2021 11:39:44

Thread: Inroducing lathes article in 303
27/04/2021 07:48:29

Your point is valid, but with a little thinking, it is not a great challenge to work out which line relates to which material.

Given the following list of materials, in what order of cutting speed would you rank them?

Tough steels, hard cast iron

Silver steel, stainless steel

Mild steel, cast iron, bronze, gunmetal

Free cutting steel, brass

Aluminium and its alloys

Plastic and wood

Thread: Gear, Gauge, or Cutter ?
26/04/2021 19:04:04

The cutter infeed, or tooth depth, is normally written as D + f, where 'f' is the clearance. Perhaps Dathan liked gears to be cut with a little extra clearance.

I suspect the calculation of 'D' will be the same whatever tooth geometry you choose.

Law gives 'f' as 10% of the tooth thickness at the pitch line, so Dathan's percentage might simply be bigger. Similarly, maybe the percentage for other geometry might differ.

Thread: Does anyone know what this is for?
26/04/2021 11:57:49
Posted by Nigel Graham 2 on 25/04/2021 23:02:13:

If so the lower wheel might be a Crimp Roll

There are a couple of challenges with the crimp roll theory. First, with a smooth upper roller, it is difficult to see how it would form a crimp. How is the metal pushed into the tooth spaces of the lower roller? Hand-held duct crimping pliers are like a pair of scissors with multiple blades (e.g. https://www.zoro.co.uk/shop/hand-tools/pipe-testing-and-inspection/5-blade-pipe-crimper-black-pvc-handle/p/ZT1010838X) that form the crimp in the gaps.

If you ran a sheet of metal through that, the part of the metal where the teeth of the lower wheels contact it would be thinned, so the overall effect would be as a stretcher rather than shrinker. It is like hitting the edge of a piece of sheet metal with the cross of a cross pein hammer: you thin it and stretch it.

Second, the lower rollers have circumferential grooves in them so the imprint would be like a series of five Morse code dashes.

If it does its work on the left side of the machine as photographed, the big gap in the centre of the machine seems somehow wasteful.

Thread: Arris rail support brackets for concrete fence posts
25/04/2021 10:01:05

Toolstation code 92651.

However, on wooden rails the tenon is cut flush with the flat side of the rail. With the brackets, the tenon is relative to the pointy side of the rail so the position of the fence with respect to the centreline of the post will change or the fence will be out of plumb if you do not modify all rails.

The screw on ones can be used with a concrete post, but it might be better to use a non-hammer drill (such as a 6mm dia. diamond tile drill) for the rawlplugs.

Thread: Calling all Colchester Bantam owners.
25/04/2021 08:25:49

Fourth post in this thread:

https://www.model-engineer.co.uk/forums/postings.asp?th=133708

Thread: Gear, Gauge, or Cutter ?
24/04/2021 14:54:19

It is a cutter for a gear shaper.

Perhaps the best known manufacturer of the machines that use it is Fellows. In the UK, Drummond made one.

There are some YouTube videos by them on 'The Art of Gear Generation' and the Vintage Machinery site has a copy of their book of a similar name.

http://vintagemachinery.org/mfgIndex/detail.aspx?id=2186&tab=3

Dathan were or maybe still are a gear specialist.

Edited By DC31k on 24/04/2021 14:56:08

Thread: Faster Screw-Cutting
24/04/2021 14:47:52

As a description of its function, 'leadscrew dog clutch' is OK. As a description of its location, it is maybe a little misleading. It needs to go immediately on the end of the spindle, before any gearing changes the angular relationship between spindle and leadscrew.

In some sense, it might be better described as a 'spindle dog clutch'; it is all about point of view - are you disconnecting the spindle from the leadscrew or the leadscrew (and all its associated gearing) from the spindle?

So, yes, it can go before a QC gearbox. It must go before the QC gearbox. It must go a considerable way before the QC gearbox, on the first place the machine sees the 'output' of the spindle.

Until I understood its operation, I often peered at the six-tooth dog clutch that disconnects my leadscrew from the gearbox, so the screw does not rotate when not required, and wondered if I could replace it with a single tooth one. I understand now why that is not possible.

24/04/2021 09:10:41
Posted by Chris Crew on 24/04/2021 08:41:44:

Something in the back of my mind tells me that Martin Cleeve also designed a similar 'gizmo'.

Martin Cleeve is generally remembered for his single tooth leadscrew dog clutch, detailed in his book and designed for many other machines by Graham Meek. It may be this that you are thinking of when Cleeve's name comes into your mind.

It achieves the same effect (stops the carriage moving under the action of the leadscrew) but in a different manner. Rather than opening the half nuts, it disengages the dog clutch using a spring action trip that has no significant delay.

The advantage of Cleeve's design is that the half nuts stay engaged so it can eliminate the need for a thread dial indicator and overcome language (imperial//metric) difficulties. A consequence of that advantage is that you have to reverse the leadscrew (maybe by a handwheel at the tailstock end) to reposition the carriage on threads where resynchronisation after opening the half nuts would be difficult.

Thread: Best way to cut/turn a 75mm Disc from a piece of Aluminium Plate
23/04/2021 19:37:34
Posted by Nigel Graham 2 on 23/04/2021 17:01:19:

However you don't need worry about the arbor thread, nor the pilot-drill, because those are supplied.

And if you do not want a 1/4" hole in your offcut?

Or you do not mind a hole, but you would like it to be no more than 4mm dia?

Or you have limited headroom and want the arbor to go directly into the Morse taper of your machine?

Or you do not like the 13mm A/F hexagon shank on a standard arbor?

Or you do not like the idea of holding a 10mm dia. SDS shank in a collet?

With holesaws, the bought-in arbors confine you to a certain path: a home brew one allows you to tailor something appropriate to your own needs. And for that, the arbor thread is about the only thing that is important.

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