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: Measuring wear on a surface grinder|
It's very possible to have the machine so worn that it produces 'bent' parts and grinding the chuck will not fix that nor will the popular test of putting blocks on the corners of the chuck and grinding them to compare the thicknesses.
I had one of these and the cross axis ways were so worn that anything I ground was convex in the short axis. i did set about re-scraping it but after a lot of work lost heart and got rid of it, mostly because I didn't have a straight edge to fit the cross table ways (you can't fit a regular straight edge in there) and because the wear so so bad that the cross slide screw and nut were trying to carry the weight of the cross slide and table.
You can use your test to check for 'banana ways' but orientate the straight edge across the chuck and check that axis. If the ways are straight it will either indicated evenly along the length or have a gradual rise or fall on the dial. If they are as badly worn as mine the indicator will fall then rise showing a low reading in the middle.
Edited By Pete Rimmer on 24/04/2020 19:08:17
|Thread: J&S 540 way lube question|
Early 640's (the ones with the straight-sided column and belt drive pump) were manually lubed saddle ways. Often neglected. The early ones also had small brass flow control valves behind the table for the pumped oil.
|Thread: Delay in dispatch and delivery|
They are probably back-logged in the system. I was in the butchers this weekend and there was a postman queueing outside the door. I overheard him saying that there were 200,000 parcels stuck at the Medway distribution centre. He said it was far busier there than it had ever been any Christmas he could remember, but they had only a fraction of the staff.
|Thread: What is this small hobbing cutter for?|
Clock escapement/ ratchet wheel. I've got a bunch of them. That one is in pretty sad condition.
|Thread: Enamel Paint|
The enamel paint I use on my machines is like that. Second coat within 2 hours or leave 6 days otherwise it will trap the solvent in the first coat and could blister.
|Thread: Angular contact bearing end float in face-to-face config.|
Mark, I suppose you have checked the bearing orientation? The axial line of thrust must be opposing for each one, so they must be front to front or back to back.
|Thread: SPACE HEATERS|
I know it's an old thread but I agree with this as a consideration.I heat my workshop with a single 2kw infra-red heater and it's 215 sq/ft so three of those or a pair of 3kw should keep the OP's work space comfortable to work in, depending on height and insulation. I have a second one but two running make the place uncomfortably warm, I only use the second if I want to do a bit of painting on a large item.
|Thread: Angular contact bearing end float in face-to-face config.|
Shimming is your only choice if you want to keep the bearings. I just had to do this to diagnose worn out bearings on my surface grinder.
Measure the end-float with a dial gauge then get some shim stock sandwiched between two pieces of scrap. Drill it through then turn the outside then you'll have the correct annular shim. You can do ID or OD depending on how you orientate the bearings.
|Thread: Did Stuarts marking blue really do that?|
The difference ,might be something as simple as the swarf not flowing off the tip smoothly. As most of us have no doubt experienced, even a tiny change in lube - a misting of wd40 or cutting oil etc - can have a huge effect on surface finish. A 3 thou cut will produce a very fine swarf and it could be nothing more than the blue causing the swarf to roll into a bunch rather than flow away from the tip.
I was cutting some 8.5 degree included-angle tapers last week and I had to experiment a bit do avoid the swarf rolling over and marring the finish. Once I got the speeds & feed right they came out very nice.
It's possible that it has an effect. When scraping something that is heavily blued you can get a build-up of blue + scraping dust that makes the scraper skid, especially if it's dried out a bit. It doesn't happen often but it does happen.
|Thread: Scraping and Shimming Myford Headstock Bearings|
Jan Sverre's videos are always worth watching. He isn't in it for 'likes' 'subs' or money, he just enjoys sharing his knowledge and helping people.
|Thread: Selecting an Engineer's level|
Quite right Michael. Add that to the fact that the most expedient way to to check for twist is the ensure that the ways are actually level both ends. They need not be and it might not even be possible, but why complicate things?
The Colchester alignment check sheet calls it a 'transverse bed level' measurement. Seems like a pretty intuitive description.
Your level is only resolving to 6 minutes of arc - that's not even it's accuracy, but it's resolution. A typical engineer's level will measure 10 seconds of arc or better, 36 times more sensitive to a change in angle.
In real terms it means that your electronic level won't register 6 thou of twist in a bed 4" wide (approx. the length of that HSS bit). It's not sensitive enough.
|Thread: Help with Maths ratio problem?|
Strictly speaking he can make 500ml of fizzy drink. 480ml of lime/lemonade mix and 20ml of straight lemonade.
|Thread: Correct boring with a steady - advice please :-)|
Hopper read my post again more carefully. You use the dial indicators to true the part with the fingers not touching. That gets the end of the part turning on-axis with no runout. Then you zero the dials and bring the fingers in until they are all touching and the dials are both zero. That means you have it constrained by the fingers AND still on axis. It's about as accurate as you can get it, the only rotational axis error then is in whatever runout you have in the 3-jaw at the other end (and he has a grip-tru so that could be brought to zero).
Setting the finger at the chuck works most times, done it many times but you can still have the part walk out of the jaws especially on thin walled parts. If you set the fingers touching at the chuck then slide it back, your fingers will be centring the part the other end off-axis by whatever runout you have in your 3-jaw. Flat bed ways have the extra potential for error by the amount of clearance between the steady and the inside shears.
Both methods work but to different degrees of accuracy.
If you have two dial gauges put one on the side and one on the top (or bottom) up near the steady rest. Release the steady fingers from the part and turn it by hand tapping it true until the dials read no runout and zero them. Now bring the steady fingers in until all three are touching and the dials read zero, the part will be running true in the steady.
If it's not round on the OD you'll have to stuff a centre in the end and turn it true first.
TBH that boring bar is too thin for that much stick-out. It might well be deflecting as you feed it in under load.
|Thread: Glass scale /DRO compatibility|
TTL = transistor-transistor logic signal, for simplification purposes it just means square wave.
The unit you have is pretty much the common standard for budget scales and head units so any of the regular scales you'll find should fit it. You'd have a more difficult time finding new scales that didn't.
See if you can find the manual for the head unit because you might want to change the scale resolution setting. If you can't you better get a scale with the same resolution as the one you already have so that it reads correctly.
|Thread: An Easter Tale of Cordless Batteries.|
I had this problem with a dead Dewalt 14.4v screw gun. The battery was so flat that the charger would not detect that there was a battery connected. My solution was to very briefly connect a 12v motorbike battery across the terminals. As soon as I did that the battery charged up just fine and has been working this past 18 months.
|Thread: Large Crane|
A job I did we used a 425tonnes capacity Sheerleg "Norma" out of Zebrugge to lift up to 400 tonnes on the river Medway. The Norma has since been scrapped but I bet that ship in the pic above could have picked her out of the water :D
|Thread: Sourcing gunmetal for leadscrew nuts.|
LG2 = Leaded Gunmetal
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