Member postings for Martin Connelly

The usual state of affairs is that as long as a 3 jaw self centring chuck holds securely then run out does not matter since you would never take something out and expect it to go back into the chuck in exactly the same way. You do all that you can without removing the part from the chuck. After that if you need to turn more features use a 4 jaw independent (typically) and dial the part in to get concentricity. I have no idea what the runout on my 3 jaw chucks is. I have never measured it and never will. If I want good concentricity in a 3 jaw to a machined surface I use soft jaws and clean them up before each use. Don't try to fix what is usually not fixable. You can grind the jaw faces but as soon as you go to a different diameter they will be out again. Think of the 3 jaw as a quick and convenient way of holding a rough piece of stock for first operations.

Martin C

Good quality cutting oil is a must.

Martin C

Forgot to mention that I think single point screw cutting is cheaper than buying dies, buying or making tailstock die holders or hand die stocks. One tool will do lots of threads when single point cutting so is a cheap option.

Edited By Martin Connelly on 13/11/2022 08:30:15

I had a parcel delivered by Evri. Inside my complete, sealed, plastic posting envelope delivery was a further plastic posting envelope that was addressed to someone else with enough details to identify that the missing item was a small and reasonably expensive piece of jewellery. I contacted the Evri courier who came to collect the evidence and said that this happened frequently. Someone in a packing department pinches the small and valuable item and hides the packaging in another bag to get rid of the evidence. The item shows up as posted in the supplier's system but it goes missing further along the line with the couriers often getting the blame. I think the evidence is passed back to the original supplier to inform them that it is occurring at their premises.

Martin C

Start the hole with a spotting drill so that the 2.5mm drill is not deflected at the very beginning. A correctly ground short series drill running at the correct RPM and feed rate is the way to go. A twist drill is like a twisted ribbon and is easily deflected by pushing it too fast and a jobber or long series drill is more flexible than a short series drill. Peck drill to remove debris as you go as well. Be prepared to replace the drill if it is not cutting well.

Martin C

Edited By JasonB on 08/11/2022 13:01:25

I've had one of these but as we don't answer calls from unrecognized numbers we let them go to answer phone. If someone starts to leave a message and we are near we can answer it if it seems legit (eg knowing the name of the person they are leaving the message for). As well as checking out unknown number online I have a second sim card in my mobile phone that I only ever use for checking out unknown numbers, and they usually come up as number not found. Any call coming to that second sim card is always going to be a scam call. My mobile phone provider often flags up incoming calls as possible scam calls, presumably because they detect a flurry of calls from the spoofed number or because other people have flagged it as dodgy.

The reason I have a second sim card is that it is the one supplied with the phone. The other one was transferred from a phone that died.

Marin C

When the phone network at work was changed over to a digital system we had to let the IT department know which phone sockets had to be left as analogue for FAX transmission and reception. Within a couple of years we no longer sent or received any as email replaced it as a means of communication.

Martin C

Even a small leadscrew can lift a tonne, I don't think the leadscrew will be undersized for the load it has to take. It may be likely that the mechanical advantage is not great so it feels like a lot of effort to raise the head but there is unlikely to be a mechanical failure. A lot of car jacks supplied with cars were/are based on a simple screw and are capable of raising one side of a car off the ground if you wanted to go that far.

Martin C

Manual for the Grizzly version of the super lux

Edited By Martin Connelly on 31/10/2022 08:23:25

I am not sure Jason. I agree with Baldric, I think he needed to be able to vary the angle relative to the top of the mill bed (hence the mentioned need, possibly tongue in cheek, for a large double sine table) and this method allows that without ending up with unwanted sideways forces from the clamping. You would still have some sideways forces but they will be considerably smaller than those from an extended stud at an angle. I would think a couple of acorn nuts on a short piece of stud would also work and be easier to set up than two loose ball bearings used at a number of locations.

Martin C

If you want to, you can run it in one configuration and treat it as a single speed single voltage motor since a VFD will allow changing the speed. You have not stated what the supply voltage is supposed to be to know which configuration suits a basic 240V VFD best.

Martin C

I have to say that having machined some HDPE just one week ago I could tell from the look of the original material and the way it was cutting that it was not the same material. The large piece of HDPE I had (Ø100) looked waxy, a bit like an uncoloured wax candle, and, when turning, the swarf came off like a piece of string being shot out of a hose. The powdery debris from cutting the gear also looked very odd. There is a possibility that what he had was more like a sintered plate of HDPE powder that was made using a heated press to form the final product. I expect this would be cheaper than injection moulding tooling and would have a shorter cycle time.

Martin C

I think you would need something a lot faster than a butane blow lamp to heat them for bending if you don't want the heat traveling up to the plastic handles.

Martin C

Dave, your comment on the apple turnover burning you reminds me of a case from my youth. In the early 70s I worked on Saturdays and during school holidays in a department store cafeteria (clearing tables and putting crockery and cutlery through a dishwasher) that had a microwave oven long before they were cheap enough to be in many homes. We used to use it to heat pies, soup, turnovers and the like. A friend who worked in another part of the department store came in on his break. He decided to grab a jam turnover for a quick snack so I suggested warming it in the microwave for 30 seconds. When he took it out he felt the pastry and decided it was not warm and tried another 30 seconds then repeated for a total of 90 seconds. When he bit into it a trickle of boiling and bubbling jam rolled down his chin scalding him quite badly and giving him a nasty blister, he was in a lot of pain but being a teenaged boy I could only laugh and tell him he was told only 30 seconds.

Martin C

I had to reduce the zoom on my monitor to get the spacing less than 62mm (my pupil spacing) to view the 3D image on the screen. At this reduced size there is a loss of detail that would probably return if I printed them off. Otherwise it was interesting to see the 3D image.

Martin C

I have a micrometer stop but it is not a great design. The slightest bit of debris makes it very hard to adjust and it is actually prone to slipping when power feed pushes the carriage against it. Often dropping a suitable length of bar between the headstock and the carriage to give a positive stop to work up to and using the compound feed for fine adjustment is the best option. Let me know if you want any pictures of it to work out if you want to make your own.

Martin C

I looked at the geometry of Elmer's wooden grasshopper right hand pivot as it is clearly constrained by the leg to travel in an arc but horizontally by the linkage. It works out from the original dimensions that the horizontal pivot movement is ±0.032" and since the arc has a radius of 5.125" this results in a vertical error of 0.0001" or ±0.00005" . I don't think I need to worry about this slight error in the motion locking everything up since I am also intending to make the pivot bearings out of some Oilon (Nylon 6 sheet with added oil) I have in my scraps collection which will add a little bit of give into the mechanism.

Martin C

I am currently doing a 3D CAD model of Elmer's wooden grasshopper (Number 10) as I want to make one at some point for one of my grandsons. As I go I am changing it to metric and making clearer layouts for manufacturing. What happens when doing one of these exercises is that as you change one dimension it can have a knock on effect on everything else. So you end up going back over previous parts to tweak positions of pivots and distances between them. I have got to the point where the crank pin throw has been calculated and after that it will be doing a similar exercise for the eccentric. I can understand how easy it must have been for people not working with CAD to introduce small errors. Once those small errors are on paper and the parts made it is probably too easy to think there is an error in manufacturing and so modify parts to ease the working of the engine.

Martin C

The people who used the radial drills where I used to work put the drill chuck in the socket and then brought it down onto the drill table or vice to secure it. They never had a problem getting the chuck and arbor out of the drill using drifts but if the arbor got damaged they were well and truly wedged into the chuck. I resorted to cutting off a number of them and drilling out the core that remained. This usually reduced the pressure on the taper enough to get the remains out with little effort. The point is that over time the chuck is being pushed further onto the arbor by both the forces of fitting the chuck into the drill (impetus due to momentum or direct pressure) and the pressure on the drill bit in use and together these usually work towards keeping the two parts together.

Martin C

I remember cutting the caps with scissors to set them off as well. They didn't bang very well as the gasses were not trapped.

Have you considered fitting an LED in place of the incandescent lamp so it lights up even at low rpm?

Martin C

Try vegetable oil painted on and left to soak for a while, then wipe with paper towel. I use it for the sticky residue of self adhesive labels and tape as well. Low odour and not going to cause issues if some drips down.

Martin C

Should add that I put the aluminium grilles in the dishwasher when they start to look a bit discoloured.

Edited By Martin Connelly on 12/10/2022 18:07:25

They are clearly clearance holes for M3 plus a large washer

Martin C