Tool Post Grinder for a Myford

[Gary C]

In the process of putting together a tool post grinder to fit my Myford. Reason its needed is to grind needles for model engine spray bars.

First engine to get a venturi and spray bar is an OS30 glow.

The needle is 1.6mm stainless so once ground will be silver soldered to the barrel nut.

I have made the mount for the grinder motor which is a 24VDC unit, ball raced and fitted with an ER11 chuck and 3mm collet.

Once happy that it fits

I finished tidying it up. Anodised the dural and chemical blacked the steel.

Still need to provide a power supply, build a diamond dresser holder and then grind the needle.

 

[petertha]

Looks useful, keep us posted. What is the nominal motor power output?

Re the ER-11 collet accessory you mounted, I assume it has a matching bore to the motor shaft OD or did you have to do some alteration to either. I've seen some 'integrated' motor/ER combinations on Ebay/Aliexpress in the 500-600 watt range, some brushed, some brushless. But the motor an goes up proportionately. Reason I'm asking is there are some nice brushless motor prospects from RC that have desirable attributes, but I always stop at the 'how to properly marry a collet chuck to output shaft'. At elevated rpms even a little bit of imbalance can start creating issues.

 

[Gary C]

The motor shaft is 5mm so a snug fit to the collet. Two opposing grub screws are used so that helps balance. I've run the motor up at 24VDC and it pulls around 1250mA and feels very smooth. There isn't a figure given for the power? Some threads I've looked at say an 8 to 10A power supply is best for routing. I don't envisage it pulling more than 3 to 4A max using it as a fine grinder. But will measure the current when I get to use it.

I looked at using a brushless out runner as I use them on planes and helicopters. This unit was under 30 pounds from Amazon so I had to give it a try. An out runner will need a matching speed controller and a minimum of a servo tester to drive the speed controller which just adds to the price.

 

[ChazzC]

In the process of putting together a tool post grinder to fit my Myford. Reason its needed is to grind needles for model engine spray bars.



View attachment 140433

Still need to provide a power supply, build a diamond dresser holder and then grind the needle.

Nice build.

Keith Appleton has a couple of videos showing how he added a Proxxon Multi-Tool to his Myford ML7R, first using a Proxxon bench-mount and later using a for-purpose adapter that Proxxon sells:

ML7R Toolpost Grinder w/Bench-Mount Part 1
ML7R Toolpost Grinder w/Bench-Mount Part 2
ML7R Toolpost Grinder w/For-Purpose Adapter

More expensive approach, but you get a tool you can use for multiple applications (Keith uses his Multi-Tool for everything).

 

[Gary C]

Thank you for those links. I did consider Dremel's and even flexi shafts as I use them with my RC aircraft building.

The 2MT ER11 chuck arrived today from RDG. I had a 24VDC 8A SMPS sat doing nothing so decided to use that for a power supply.

I don't yet have any Dremel #85422 silicon carbide wheels which are required for a better "first" finish. The point is then polished with #425 disc.

Anyway, haste got the better of me and I had to do a trial run. Some rags removed below for the photos.

Both images after I ground the needle.

Should have took a better photo of the point, apologies for that.

Because I used stainless wire, I had to silver solder the wire to the barrel nut. Took longer to clean back up than to do the soldering!
Will be using piano wire in future.

I've ordered the right wheels and will do another assembly. The barrel nut is made from brass M4 spacers as half the job is done for you.

Power supply

 

[Bazzer]

Nice work there, I learned to fly RC using a OS Max 30 back in 1976.

Are you using the engine for CL stunt?

B.

 

[Gary C]

Nice work there, I learned to fly RC using a OS Max 30 back in 1976.

Are you using the engine for CL stunt?

B.

The engine will go into a stunter. I have a large collection of engines from over the years but none that are "for stunt"use so I picked a few up on the bay to do venturi conversions.

 

[clockworkcheval]

Looks quite solid and impressive! In my shop I use Proxxon BFW 40/E with various holders for the lathe, the mill and on the tool grinder. If on the tool grinder you run the Proxxon in reverse your get a good grinding surface speed and excellent dimensional and surface quality on small rotational components, see picture. For internal grinding on the lathe the BFW 40/E is somewhat limited so I got for internal grinding the Proxxon LBS/E which has a long slender nose which gives good support deep in the part. See picture.

 

[Gary C]

That looks good and solid. I do like the long nose option as well. Thank you for the images.