Member postings for Huub

It seems these castings are pretty expensive. For that price you can get a 3D printer and make the moulds yourselves.

I have bought a 3D printer last year (artillery) and it worked out of the box (1 hour setup). Then I spend a few weeks of learning Freecad (every evening 1 Youtube video) to make 3D models. Now I wished I had done this years ago.

Printing the moulds doesn't take much time. It is just a matter of inserting the USB stick with the file to print. The printer, can than run,unattended, for hours.
The cost of materials (filament) are low (20 € / kg). In general, the material cost for my 3D printed parts are comparable to metal stock.
Making the 3D model can be time consuming. I don't think you are the first that wants to print a mould. Aren't there any 3D models to download?

Edited By Huub on 29/05/2022 22:38:29

For aligning the lathe you must not use any support.

To improve the finish at the far end of the bar you could:

• lower the RPM (less resonance)
• reduce the cutting depth (less cutting forces)
• use a polished insert for aluminium (less cutting forces)
• use a thicker bar or tube (more rigid)
• use a shorter 4"bar (more rigid)
• use an aluminium bar because it is easier to turn to a good finish (less cutting forces)

If you place a Dremel grinder in the tool post, you can grind the rod to final diameter. Due to the lower cutting forces, the rod will bend less. For Delrin, you need to run the Dremel at low RPM to prevent melting the Delrin.

More O-rings will support the rod better, especially if the inner diameter isn't close to the mandrel diameter.

In stead of drilling to final size, you could ream the rod (from 2 sides). That will give a pretty tight fit on a 12 mm mandrel. My standard length 12 mm reamer could ream about 120 mm deep.

I reduced the saddle play by milling the "press boards" on both my lathes. The play left will be about 0.01 mm or less.

On the small lathe, I also added 2 spring loaded ball bearings. They pull the saddle on the bed if the load is not to heavy. If the load is to heavy, the old "press board" takes over.
If the bed is worn, you need more play but the bearings still pulls the saddle on the bed.

These changes improves the repeatability/accuracy, especially when doing shallow cuts.

Also the yearly maintenance takes a few hours less because the play doesn't need to be adjusted any more.

For the foto's view my album (Carriage Saddle Press Board)

For the description PDF

Edited By Huub on 20/05/2022 22:10:12

Edited By Huub on 20/05/2022 22:12:24

Edited By Huub on 20/05/2022 22:17:15

I have several metal oil cans supplied with the lathe and mill and they all leak. I have a 30 year old simple plastic can that doesn't leak and I use it in any orientation.

This type of oil can I have:oil can

I looked up reaming tolerances in a PDF from Phantom (Don't know how to upload this PDF).

For a 7 mm hole H7 you should use their 7.01mm precision reamer. They don't spec the tolerances, just the reamer size to select.

D8..D12 are also tolerances, couldn't find D4.

If you really need H7 then you should buy a quality tool and use the advised hole drill diameter.

I have reamers from HBM (Netherlands) and most of them are way (+0.03 mm) out of spec.

When the O-ring gets compressed, it will get larger in diameter. It will sure hold the delrin tube good enough for turning. I use the same method to place a chuck stop in the spindle boring.

You should not use chamfers. The O-ring should only expand in one direction. Turn a 3 mm long 8 mm shoulder at one end of the bar and a 4 mm deep 8.05 mm pocket for the shoulder at the end of the other bar.

The 8 mm diameter and 2 mm O-ring thickness will give a starting diameter of 12 mm. That should do the job.

You only need 2 O-rings, one at the beginning and one at the end of the mandrel.

I also used G type (CCGT060204 for aluminium, 0.4 mm nose radius) insert on steel to get a good finish when doing shallow (0.01 mm) cuts. These polished G type inserts are very sharp.

I get the best finish on steel using a M type insert (DCMT11) that has a 0.8 mm nose radius running at 150 mm/min (Vc). When using a new insert, I can cut 0.02 mm. I have ordered some CCMT060208 inserts last week to see if the nose radius or the geometry makes the difference.

You should try to do deeper cuts at high RPM. To turn the correct diameter, do the last 2 cuts at the same depth and measure the diameter before each cut.

Cryspin has made a video on how to accurately turn a diameter. Accurately turn a diameter

Edited By Huub on 12/05/2022 23:00:00

Nice to see you can make great things using a small tools.

You could run this automatically by using the Freecad assembly Animation feature

Thank you for sharing. I use POM for my magnetic holders and didn't expect any metal would be "magnetically" comparable.

You could try black POM. To glue it you need a special glue

POM glue

There are others types of glue for POM and other plastics.

Normally I do Metric threading at 90% height of the nominal tread height (top to bottom).
For a M5x0.8 mm bolt I turn the stock down to 4.91 mm. For a M5x0.8 nut I turn (drill) the hole to 4.22 mm.
That about 0.09 mm less in diameter makes a huge difference in the threading force needed.

According to the data sheet in my threading tool set, I should use a 4.2 mm drill or 4.9 mm stock!!

Edited By Huub on 26/04/2022 23:10:24

Above 8mm, I do not use a die but cut the threads on the lathe using a threading tool.

For more grip, I use a hex collet holder (ER32) placed in the chuck.

I have a small hobby quality bandsaw that is portable and can be placed under my desk (run out of space). It uses a 10-14 TPI M42 blade and it does perform very well. I am more afraid cutting aluminium than cutting steel. The work holding could (and should) be better and when I have time, I will improve it.
It cuts effortlessly straight and a lot faster than my manual saw.

I make a lot of (prototype) gears in HPL, POM, PVC, and aluminium.

PVC is pretty soft and super easy to clean (deburring), just use a (nail) brush.

HPL is the cheapest and easily available. Cut it in one pass and use a second blank on the back to prevent chipping of the first blank. After cutting, the gear is done, no deburring to do.

UHMPE (old meat chopping plate from the kitchen) is soft and eays to cut, but deburring takes some time.

POM is super easy to cut but, compared to PVC, not as easy to debur. POM gears are pretty strong and durable. They are often used in small lathes.

Edited By Huub on 13/04/2022 22:12:57

There are a lot of Arduino example projects for a piezo buzzer.

Arduino piezo buzzer example

Robin,

When you start using Freecad you probably run in to the "topological naming" problem. Basically this is an old hard to fix bug. The Freecad WiKi has a page about how to solve and prevent the "topological naming" problem.

Freecad Topological naming problem

Huub

I once replaced all my POM lathe gears for (self made) aluminium gears. They where to loud so I put the original POM gears back. Until now, I haven't broken a POM gear despite my abuse of the lathe.

I have made a post and video of how I make my gear cutters and gears. Maybe it is helpful.

Making gear cutters and gears

I really understand your feelings. At the start when so many things went wrong, I often got frustrated and considered selecting another package. Now I have learned the pitfalls, I am glad I continued using/learning Freecad.
I think that most CAD packages have a steep learning curve.