Next up, upgrading the Sherline to 10,000 rpm pulley.
After the failure in removing the roller from the fixture, I wrote to the Thai gentleman again seeking his advice. While waiting for his reply, I decided to drill through each recess with a smaller diameter size drill. This way, I can tap the rollers out after they've been machined. It will be tedious doing it this way as I'll have to re-indicate the fixture for every batch.
It was nerve racking watching the mill went round doing its job. I was so afraid of breaking another endmill. I was told that with endmill so tiny and my max. spindle speed at 2800 rpm, I should go no more than 56mm/min feedrate and at DOC of 0.2mm per pass. It will be painfully slow... For this roller, I went at 100mm/min instead. It turns out well except having to spend quite some time deburring the tiny spokes. With my "old flower eyes" (long sightedness, started when I crossed 40...), it was painfully difficult.
Next up, upgrading the Sherline to 10,000 rpm pulley.
I finally got a reply from the Thai hobbyist who posted his setup of milling the Tamiya 4WD rollers! It was after my family dinner yesterday that I requested my sister in law, whom is s Thai, to help type the message in Thai on his Instagram. He responded rather quickly this time and with good English... lol. Anyway, he shared that he cut the shapes in acrylic 0.05mm undersized.
The roller blanks were then tapped in with a soft mallet of sort.
I dug through the pile of acrylic sheets I bought several years ago and found a suitable piece to make the fixture with. It measures 200 x 100 x 10mm. I did up the CAD drawing of what I need and went to work with the CNC mill.
The pics will tell the rest of the story...
Once I figure out what I can do to quickly zero in my spindle to the plate, I'll mill the circular recess to fit the rollers and start the job in batches. Maybe I can drill a hole at, say, (5, 5) and press in a short section of a hollow metal tube. This will help to dial in my X and Y axes. As for the Z axis, maybe I can glue a piece of thin metal sheet of known thickness for the touch off.
Busy day today at home. We hosted steamboat lunch and dinner at home for my wife's family and mine. I sneaked into the workshop in the afternoon to figure out how to use the centering indicator I bought many years back. This round, I managed to figure it out.
I sought for suggestions and help over at MetalworkingFun forum. Those guys there are just superb! Suggestions poured in and with so much patience! Very friendly bunch of people. The thought of using double sided tape came to my mind when a gentlemen the spoke about using some kind of tar to hold the rollers while machining. Bought a big roll of "super sticky double sided tape" from Horme after dropping my colleague off yesterday. This round, the roller didn't move! One problem down. The next to figure out is how to zero my part more accurately. Check out the pics of the finished rollers and you'll know why.
I'm quite happy with the result from the 2nd attempt. Closer inspection of the part revealed that I may not have found the exact zero of the axes though I'm very close. I'll do the next 5 and submit for testing before moving to the next spoke design.
My dad has also commissioned me to make a batch of stainless steel bushings for his dispenser. I'd the CAD done last night and should be able to machine a test piece next week to check fit.
It has been a while since I do any serious work on the lathe. After fixing up the scale, the carriage was reinstalled and I took some time to take out some slack in the hand wheels and the screws. Turning is a little tighter now but still rather smooth. To get a proper feel, I chuck up a small piece of aluminum and did some test.
Come to think about it, if I'm to make the wheels from scratch, I don't really need to face off the part off side of the wheel. Reason being, most of its face would be recessed and spokes milled out.
Do let me know if you have any suggestion or spotted mistakes. I'm still very much a newbie though I've had my machines for 4 to 5 years.
I spent the afternoon in the shop after I decided to tap the centre hole of the fixture M4. The fixture was completed quickly and I moved on to work on the M4 screw to fit the task.
Being off the CNC mill for so long, I was a little wary. Went through the BobCad simulator several times before committing to the job. The GCode was transfered to the workshop PC, which is still running Windows XP. After painfully setting up the work and checked through several times again, I hit cycle start... Midway through the program, I saw something that shouldn't happen, the wheel was turning in the fixture! I did what I shouldn't do, using my fingers to hold the wheel from turning...
Anyway, the wheel came out bad. I'll have to re look at workholding before continuing with this job.
I was studying the few pics of the Thai hobbyist milling the wheels. I suspect the use of superglue. No screw to hold the wheels in place for machining. Another possibility is the pressing of the wheel blanks into the plastic sheet with the hole slightly smaller than the wheel diameter. But will that provide enough hold to withstand cutting force? I'm already milling at 0.25mm DOC per pass, feeding at 200mm/min. Very very light cut...
Had a "quickie" in the shop before sending Ruth to her class. Whipped out the Bosch power drill and started where I left of few hours ago. I couldn't seem to push in any further after going in a short distance. Tried increasing the speed and finally get to the depth I want.
After this, the rest was a walk in the park...
I've to think of a way to deal with the wire, especially when moving the carriage towards the tailstock end. The wire has the tendency to fold into the chip tray. Another thing to look at is some way to cover the scale from chips and coolant. Can't think of anything at the moment.
Hope I can get back to work when I get home later.
Been wanting to fix up the DRO on the lathe, at least on the Z axis, for a long time. The Igaging scales have been sitting underneath the bench for several years waiting to be used. The main reason for the scale? I've been missing count when turning, resulting in inaccurate parts being made. Since I've taken a new job to make some wheels for slot cars, I might as well use the opportunity to get this going.
Being stupid and clumsy, I dropped the Mitutoyo DTI. The problem moved side to side after the accident. When I tried tightening the screw next to the probe, the wiggle didn't go away. So I decided to remove the screw to see what may be the problem. Big mistake! Several micro size steel balls started dropping out... Arghhhh... I've 3 dial indicators but only 1 dial test... Why?!?!?!?!
I'll pray for no mishap tomorrow when I started drilling and tapping the holes for the scale. It was an eventful night (or should I say, morning...) with my broken DTI. I checked Element14 for the price of the same unit, it is listed as almost S$180... I might have to bite the bullet and purchase one as a replacement as I don't know how else to indicate in my vise and parts without it.
After a lovely evening out having dinner with my family, I continue with my work on the wheel. I wanted to do up a fixture to hold the wheel blank in place during the machining of the spokes. The fixture will hold a piece of blank for now. Since I've only 4 pieces to work on at this stage, it shouldn't take very long doing one at a time once that part of the job starts.
Looks like I can't carry on tonight. Will have to make a trip down to Chan Man Lee to buy the M3 tap. Problem is, I would be able to get back to the shop till after Tuesday - roadshows on both Monday and Tuesday night.
Late morning today, I decided to complete the job I started on repairing the leaking water closet. Once again I remove the tank from the bowl and uninstall all the existing components. New flushing system and fill valve mechanism were added to the tank. And with the installation of the spud gasket, I've leakage no more!!!
Enough of words, let's see some pix!
One thing I realized when working on this project - I always don't have the right tools when the need arises. Like for this instance, none of my spanners can be used! I've to rely on the adjustable wrench, which is a pain to use for such tight corner. In fact, I've almost all the spanner sizes from 5mm to 26mm, but not a 20mm... And I've 2 of 18mm and 19mm... Thank God I managed to get through with the job.
Now that I've some confident fixing a toilet tank, call or write me if you need help. For a fee of cause... Lol. Tedious job.
The leakage of the fitting at the master room's toilet continues after I tried fixing it during my annual leave in June. It irritates me so much that I told myself that I got to get it fixed today. Went out to the hardware store nearby and bought this:
I was told by the hardware shop that I'll need to remove the entire water closet to do the replacement. I was a little hesitant but went ahead with it.
It was a messy job, especially with parts soaked in water for so many years. Managed to remove the water closet and dismantle what's required. Then I realized that the new part is too big to fit I the water closet... *slap head*
Anyway, I tried cleaning the rubber seal as best as I could, hoping it is just the seal causing the problem. Will be heading back to the hardware store to find the right part to complete the job.
This is what I got meddling with something unknown to me...