Member postings for Huub

I didn't know Stepper Online had these Nema sized BLDC motors. I think this motor could be a candidate for my lathe toolpost drill.
A 24V bldc driver for this motor could be BLDC driver

My current candidate (bought one already) is this 20V cordless BLDC drill from Lidl. The parts could be used for making a tool post drill.

As a lathe spindle motor, this one has very little torque. But for making small parts, it could be OK.

edit:

Stepper Online does have a "suitable" driver and controller: Driver and Controller

Edited By Huub on 06/11/2022 12:57:32

You want the led running on 12V. The current = 0.27A. Add a second resistor (serie) that has a voltage drop of 9V at 0.27A. That is a resistor of (9 / 0.27) 33R0.

So you don't need a Zener.

You could replace the 2R7 resistor by a 39R0

When the clock maker stopped maintaining my fathers clock on a yearly base, he gave me some oil and showed me how to oil the clock. I have used this oil for 30 years to oil my fathers clock (and others) and it is still running.

Today it is the first time I looked what type it is. It shows "Shimano selected by Koga". Some kind of bicycle oil?

You could make (turn) a backplate plus collet holder your self on the lathe. I have made several and it is not difficult. This self made collet holder will run true, probably better than any thing you can buy.

Give it a try, it will cost some time and a piece of steel.

I also use wooden bushes at the end of the spindle bore. When the stock is thick and heavy, I use bushes to reduce the load on the spindle bearings, even if the stick out is minor.

Edited By Huub on 06/10/2022 23:19:16

Edited By Huub on 06/10/2022 23:19:41

Edited By Huub on 06/10/2022 23:20:07

Edited By Huub on 06/10/2022 23:21:00

I have both (angle and callipers) from Lidl. They perform well and are accurate enough for hobby users. I don't remove battery's from any gauge and I don't switch them off. Batteries cost only a few penny's (Netherlands) and the on/off button of my lathe gauge has worn.

I have a calliper (€30,--) that keeps the zero point even when switched off. That is really nice to have. It saves a lot of time and prevents false zeroing.

I am testing a 600W Lichuan servo motor (as second motor) for the lathe. I run this motor in speed mode (turning) and step/dir mode (Spindle positioning). When I am done testing, and all is going as expected, I want such a servo motor as the main motor.

To cut titanium, you need a sharp tool or a lot of power and rigidity. Grinded( HSS or Widia) tools are usually sharp and will cut titanium nice but not for long.

A carbide tool insert is normally a moulded one (DCMT070204, Diamont type, 7 mm long, 2 mm thick, 0.4 mm nose radius). The DCGT0700204 is the same size insert but its dimensions (accuracy letter G) are more accurate. To get that accuracy the moulded inserts are grinded. This grinding gives them sharp edges.
Sharp edges are good for plastics, aluminium and also titanium. Because the cutting forces are lower, grinded inserts are also an option to cut difficult materials on hobby machines. If you use a smaller nose radius (DCMT070202 0.2 mm nose radius), the radial cutting forces will be a bit lower.

Other issues. If 304 is not the best grade to use, what is best? Yes, it does need to be stainless.

I have only machined 304 on my (CNC) lathe and it took some time to get the job done properly.

From what I have read on the internet, 303 is better for machining on a manual lathe. 304 is more corrosion protective.
The 400 series are easier to machine but are not as "stainless" as the 300 series
The L (leaded) series 304L, etc are better for welding.

I would go for 416 or 304.
You need sharp tools. If you use HSS tools, resharpen them often.

Edited By Huub on 12/09/2022 15:00:42

Mark,

You have done a nice job and now have a back, time and space saving setup as result.

I would:

• cutoff (3) corners so that the part fits in a 3 jaw chuck. Draw a circle and use that as a guide
• drill a 24 or 24.8 mm hole. Be gentle, the work holding isn't that good.
• turn or ream the hole to 25 mm
• face both sides gently.
• Make an 25 mm arbor to hold the part
• Turn the outer diameter
• Drill and tap the hole for the grub screw.
• Check the length of your tap before you start. 25 mm is on the limit. If you bore the hole thicker over a length of 10 mm, a standard 5mm tap will do

If you have a mill, you could also make the 25 mm hole on the mill.

If you face your 12 mm part, it won't be 12 mm thick after facing.

If this is your first exercise in stainless, take some practise cuts at this diameter on another piece of the same type.

If you use the jaws to hold the 25 mm hole, check if the hole fits the jaw. My 80 mm chuck can hold 23 mm on the outside of the jaws.

if you hold the part in the jaws, check if the jaws don't hit the lathe when turning.

Edited By Huub on 10/09/2022 23:39:19

I use 3% silver 97% tin (common lead free plumbers tin) for (soft) soldering HSS toolbits on steel tool holders for making grooving, parting and threading tools.

I think the spindle is damaged during use because It is likely the bearing and spindle are machined in one fixation to avoid runout.

You could repair the seating of the nose and/or the taper on the lathe!

Edited By Huub on 09/09/2022 09:15:28

If "there is some unevenness and roughness when turned manually" and this is at a low preload, the bearings ar worn or damaged.

You should measure the runout at the inside of the spindle taper. If that is not possible, then on the outside of the chuck taper.

If you use a drill chuck (not a collet) than the runout of the drill chuck is probably more than the runout of the spindle.

When I lock the tailstock, the alignment shifts 0.02 mm. That is 0.04 mm in turned diameter. I align the tailstock locked so turned diameters will be OK.

On my lathe (Chinese HBM BF290 & DC300), drilling accuracy using the tailstock is less accurate then using a drill in the tool post (CNC drilling).

For the BF290, when the tailstock base is locked, there is absolutely no movement in the tailstock. The alignment after locking is also very repeatable. I have never checked the small DC300 for this.

.

I use a 4 mm (thickest part) centre drill in a collet holder (have a spare) to get the most accurate centre hole. The centre drill is made of HSS Co 5%. These are a bit more expensive than plain HSS but last longer.

A common HSS centre drill or short spot drill will also do well.

Checkout this video for Tailstok Alignment

I rough grind my tools by hand using the angle grinder. Finish the rough cutting by hand using the bench grinder (white stone). Finally I grind the tool using a diamond wheel (80 mm, € 5,-- version) using a holder having the right angle(s). Regrinding using this holder takes only seconds.

I stack different holders to get the right angles. I do not grind the top of the tool. When using this diamond disk, I do not need to wed the cutting edges.

Beware, HSS Co (cobalt) dust is toxic so use a good dust mask.

Edited By Huub on 07/09/2022 22:28:07

A M5x0.5 thread at 6g tolerance should have an outer diameter of 4.98 mm max (see link).

6g external thread

I only use none adjustable dies. I would turn the bar to 4.95 mm.

This die has a chamfer. Turning also chamfer on the bar will make it more difficult to get the thread starting because more threads are engaged at the same time.
I only chamfer the stock when doing CNC threading to soften the sudden increase of the load when the cutting tool starts threading.

Edited By Huub on 05/09/2022 23:14:28

You need some clearance when you grind the tool. The thread is cut at a small angle (helix angle).

Look at this site Grinding a 60° lathe threading tool for some information

For a first try, it looks a whole lot better than my first cut thread

I use Freecad and it takes some time to get used to it.

You need to draw a construction line from the centre of the saw blade to the cutting edge. Than you can set the angle between the cutting edge and this construction line.

You draw 1 tooth and use the polar pattern to draw all other teeth.

To bent 2 teeth, you draw 2 teeth and project the sketch on a curved surface. You can use the Curves workbench for this. Curve workbench

If you want to change the height of the teeth, drawing a bunch of teeth at the right height, projecting them on a curved surface and than making a polar array is an option. I can't think of an easier way at the moment.

To make life easier, you need to set all dimensions in a spreadsheet. The dimensions in the drawing can than be changed by just changing the dimension in the spreadsheet.

In the spreadsheet you can make a configuration table having different dimensions for different saw blades. You can then check your design changes for different saw blades by just selecting the right saw blade.

If any of these techniques is unknown, use Youtube to learn it.