Member postings for Pete Rimmer

John if you look at the table I posted in that link it gives the info for all tooth counts from 10 to 33. You look up the tooth count in the first column (12 in your case). Now take the number in the second column and divide it by he DP (20DP for your Myford). 1.2477"/20 = 0.062385" or 62 thou. Add this to the diameter that you would get from the normal calculation for gear diameter.

Well done John. The actual correct shift for a 12T 20DP pinion is 0.062" larger in diameter but for a change gear it hardly matters.

Either way it's a sad sight and heartbreaking for both the seller and the buyer. Looks like it was a nicely kept machine.

I don't like them at all for cutting anything metal, and I use them for a living.

Edited By Pete Rimmer on 05/06/2022 12:27:12

My advice is get a 5" grinder. If you're using the thin cutoff discs you'll get a lot of extra use from that extra 1/2" of disc and the extra 1/4" depth is very handy sometimes too. The smaller the diameter of grinder, the more disc is wasted if you're cutting stuff like sheet where the housing will foul the work.

The 4" discs have a smaller hole than the rest (4.5", 5" and 9" are all the same) so I would avoid that because it limits your choice of disc.

You can use a 4.5" disc on a 5" grinder no problem and if you choose your model carefully you'll find a good one with a smallish gearbox housing for maximum disc usage but you can't put a 5" disc on a 4.5" grinder without removing the guard.

The cheap ones are 'OK' for light use but they don't like heavy cuts and the blade guard release lever tends to be bulky so it's the first thing to foul the work.

Yep 100% wrong type of pallet that load was destined to fail (or fall). The edges of the base are mid-span on the slats and there's no bottom stringers so when the truck went round any bend the machine starts to lean and slats will bend then snap. If it has a sheet of ply on top, even 1/2" ply, it would probably have been ok. Using a blue pallet would have been even better. The ratchet strap is inadequate and it should have been around the slat the machine was sitting on not the outboard one which would pull out the nails.

The driver should have refused it as an unstable load.

One reason why a 17/34 might be hard to find is the 17t gear minor diameter is going to be very close to the hole size for a standard pin it might even be smaller. I can't check it out right now until I get home. You might be better off going with a 34/60 pairing which is the same ratio but a much stronger gear.

TBH I would not put too much weight on advice given by someone who demonstrates lapping in cross slide ways with loose abrasives. It might make good sense to the unwitting, but lapping is the very last thing you should do to finish any moving way.

Thanks Andrew. Your dims work out 3.486" / foot of taper my guess is that it's 3.5" / foot given the difficulty in measuring such things precisely.

I think that our ID grinding heads are very similar if not identical. The covers are obviously different because the MG9 motor is in the cabinet.

Regards

Pete

Mine is the same design Andrew. You remove a cast iron name plate then bolt the internal head in it's place. Remove the belt cover and bolt a large cast ally pully to drive the head with a flat belt and fit a cast ally belt guard.

My arbor nut has a 5/8"-20tpi RH thread and passes through 0.442". Does that sound similar to yours? If so I'd love to get some pics/dims of whatever factory arbors you have.

Also, how are your wheels retained? LH screws?

I knocked up a quick and dirty arbor to get me through the job at hand. It worked appreciably well but since I didn't have a LH retainer I had to watch for the retaining screw coming loose.

Incidentally, I found an arbor in the box of bits that doesn't belong to my grinder, it's much too large. I have no idea what it fits but the taper is a very close fit so I'm guessing it might be for a MG12 or some other ID grinding head. If anyone can identify it let me know please. I've put the basic dims below.

I have a MG9 grinder which came with the internal grinding attachment. It has one single arbor for holding ID grinding wheels which is obviously home made. I want to make a selection of arbors for the vaious grinding wheels that I have, it would help me a lot if I could get some pics and/or dimensions from anyone who has them.

The arbors have a steep cone that locates in the spindle and is held in with a collet nut.

Can anyone help me with this?

Regards

Pete.

You can buy them. Here's mine.

https://www.instagram.com/p/CdL0KC6qVqs/

If the error is in the top-to-way thickness there's nothing you can do to adjust it out. It's a very simple check you could even use a digital caliper if there's no micrometer handy. Checkig anything else before this basic check is quite pointless.

Measure from the flat way, the part that is actually in contact.

First thing to do is measure the thickness of the table from the top surface to the bottom flat way at the four corners with a micrometer. If they are not all the same you're not going to adjust it out.

Something like this would run it. Big name reliable brand, easy to install and set up. You can even download their free software and knock up a cheap patch lead to configure it from your laptop.

**LINK**

What size motor isit on your machine?

The white box is a NVR starter you won't be able to use that but you most probably would be able to use the original drum switch to the left of it.

EDIT you could use the NVR as a power switch to supply the VFD but you wouldn't be able to use it as a start/stop and depending on what model VFD you get using the E-stop on the NVR might invoke motor braking or it might allow it to run down normally. Killing the power to a running VFD is not recommended.

Edited By Pete Rimmer on 09/05/2022 21:58:26

Don't worry about going back to 3 phase after using a VFD you'll never want to.

I'm not familiar with the boxford switches but if they are momentary you'll be able to use them with a 3-wire control setup, if they act directly on the contactors it's a lot less straightforward;. TBH you might be better off knocking up a simple pendant control. Few, rev and speed can be done with a 3-way switch and a potentiometer is no time at all.