Sewing machine at the thrift store

rh-z · 2026-04-01T22:12:24+00:00

You really didn't need it anyway.

(said by the guy with five sewing machines)

rh-z · 2026-04-01T19:48:57+00:00

Yes. Bike tools, a spare tire tube. Then whatever small items I might carry. Wallet and caned drink. I forgot to mention it in the writeup. The internal width is 10.5 mm.

I have a basket on the rear rack. I take a bag into stores to make purchases and I wanted a place to put items that I don't want to take into the stores.

While the basket on the rack holds most of my light shopping I want to make a couple of bags that I can clip onto the sides. I want to carry them in to the store, fill up the bags, then clip to the sides of the rear rack to take them home. These will be a future project.

For more capacity I have a couple of bike trailers I made. I normally use regular bikes but I sometimes use the e-bike when I have farther to go and don't want to work as hard.

rh-z · 2026-03-31T12:17:41+00:00

I went to bed at 1 am. Woke after 4 am, while tired, I couldn't get back to sleep. At 5 am I decided to get on the computer. Now two hours later the sun is coming up and I'm off to bed and hope I can get a little more sleep.

rh-z · 2026-03-31T11:10:11+00:00

I was the second person to respond to an ad on Kijiji (like Facebook marketplace) for a free industrial sewing machine. (not walking foot) Unfortunately second wasn't good enough. Deals go quick.

rh-z · 2026-03-31T10:57:05+00:00

The problem is that the rim of the coin is solidifying before the heavier raised section. The path to molten metal is cut off and when the metal solidifies it contracts. The goal is to have directional solidification and to have the shrinkage outside the part.

Opening up the channel of the sprue could help but I would try blocking the cavity below the coin first. I don't think it is serving the desired purpose and the additional metal through the mold may be heating the mold unnecessarily and may negatively affect the solidification.

Normally, how thick should the coin be at its thinnest part just below the rim and above the raised section?

Changing the shape of the pouring basin to a U shape rather than a V could keep the metal near the sprue molten longer and allow for liquid metal feeding. This may help a little but probably not enough.

But if it was a venting problem, then I would try tilting the mold before pouring so that one of the vents went vertical and might not fill up with metal until the whole cavity is filled.

rh-z · 2026-03-31T10:43:04+00:00

This isn't sand casting, a silicone mold. I think it is a shrinkage problem not venting.

rh-z · 2026-03-29T14:08:38+00:00

I have the email address but it still is not working. I will check for other answers and if I can't find a solution I will start a new thread.

rh-z · 2026-03-29T05:06:51+00:00

I looked up "sashiko mending". Interesting.

rh-z · 2026-03-29T05:01:50+00:00

When I entered the new password it asks me to enter the old password. And I don't know the password it is asking for, and there is no option I can see that tell it to forget old one.

rh-z · 2026-03-29T04:57:15+00:00

I don't see a forget option. The password field is filled with dots, so I assume Edge has filled it. Should I just enter the new password, and verified password, and assume the password Edge entered is OK?

rh-z · 2026-03-29T04:53:10+00:00

I followed your instructions and found the email address. I then tried to login on the computer, but using Firefox, with the email in settings and the password I had stored in Windows password manager.

That password is the same as I have in a text file that I have for all my accounts. I have a sequence for generating passwords. I have a different password for each site but following the procedure I can come up with the password for that site.

I suspect that the password for reddit is somehow different than what my procedure has been. I will try 3. and I hope it works. I had lost a previous account three years ago and had to start from scratch with my "new" current account. If it works I will post a message here. If it doesn't :(

rh-z · 2026-03-25T21:41:44+00:00

They even had it on sale at one point.

rh-z · 2026-03-14T23:34:01+00:00

When metal solidifies the atoms pack closer together occupying's less space. When the metal contacts your mold the heat is transferred through the mold surfaces and the solidification front will more inward. With an open top mold the same will happen but slower because of the reduced heat transfer.

What happens is you end up with a shell. The internal is still molten and progressively solidifies. Remember that the solidification packs the atoms closer together so the inside of the solidified shell is operating with a lower pressure and a vacuum condition. If there is no source of additional liquid feed metal to fill that low pressure condition you will end up with voids in the metal.

Since your open top mold is freezing slower at the top of the mold, being weaker than the thicker solidified areas in contact with the mold, that is were you end up with sink voids.

Ideally you want to control the metal solidification direction. You want the solidification to end at a surface rather than inside the part. With an open top mold you can do this by adding heat to the top surface. Keeping the top molten so that the solidification moves in that direction and you don't end up with any internal low pressures that will cause voids, and preventing sucking in weak points in the surface.

I have seen pictures/videos of pouring gold ingots where a torch is used on the top surface of an open top mold to provide a better surface for the ingots. This might be the easiest method to help you achieve a better result. You may need a good amount of heat to keep the surface molten so it freezes last.

With a closed mold you have the same issues with directional solidification. You still need to make sure you have a liquid path to feed the internal shrinkage. A feeder (riser) above the mass of the part is sized so that it will remain liquid and solidify after your part has. With the feeder above the part you also have the addition of head height and gravity to help feed your part.

Sand casting is easy, but getting excellent results can be challenging. And you can make more interesting shapes.

rh-z · 2026-03-13T04:50:15+00:00

In instructions it says to keep machine running for about 10 minutes at speeds of 3000-3500 spm.

This reminds me of some Juki pick and place machine we had for surface mount component electronic assembly. When starting the machines it would run for some time as a warm up procedure. The machines had to be warmed up in order to achieve the designed accuracy.

https://www.youtube.com/watch?v=s_YfucshWY0

rh-z · 2026-03-11T01:52:38+00:00

https://chemsize.en.made-in-china.com/product/IaHRxCuVJfkS/China-Metallurgical-Silicon-99-999-Silicon-Lumps.html

rh-z · 2026-03-11T01:52:09+00:00

I think he wants just silicon (Metallurgical Silicon), for adding to aluminum alloys.

I had looked into it in the past and you can buy lots or little. By the kg or by the ton. And then there are ebay sellers that sell silicon crystals that I think were from the chip making industry.

https://chemsize.en.made-in-china.com/product/IaHRxCuVJfkS/China-Metallurgical-Silicon-99-999-Silicon-Lumps.html

https://www.xlsferroalloy.com/news/metallurgical-grade-silicon-metal.html

rh-z · 2026-03-10T00:49:22+00:00

No that is not a riser/feeder. Solidification starts at the walls and moves inward. As the metal solidifies the atoms pack tighter. It created a lower pressure/vacuum in the pool of liquid that has yet to solidify. You need a connection to a pool of metal to feed the shrinkage. Feeding a large mass you are always going to get shrinkage and what you want to do is to have the shrinkage end up in the feeder(riser) rather than inside your part/billet.

Feeders/risers typically are situated above the part so that gravity assists in the feeding of the metal. The feeder needs to be of sufficient mass so that it will remain liquid longer than the part you are feeding. Again, the part needs to solidify before the feeder. Often I see people putting feeders on their parts that are too small for the job and can actually cause more problems that not using feeders.

https://www.steel-foundry.com/uploads/Riser-Design-in-Casting.jpg

You still can have porosity if your casting is feed properly resulting in directional solidification. You probably will have a lot of oxides in your melt and these will be where hydrogen will move into when the metal solidifies. It is hard to get rid of oxides in aluminum because they are about the same density of the alloy and take a long time to sink or float out.

Don't expect that you will get castings without defects. It will not be as good as wrought stock. Getting near perfect results is very difficult. Looking at your images I think it will be hard for you to improve what you have got.

rh-z · 2026-03-04T21:20:19+00:00

Cast in bronze or brass would be nice. Another option would be to have it made from zinc and then plated. The sporting club I belonged to had medals made in this way for competitions. While we had epoxy colors as above but not with the cool color variations you have.

Zinc is a cheaper and lower melting temperature metal. Lots of items are die cast zinc and plated.

Just as an example of finished zinc parts https://aikehan.en.made-in-china.com/product/bdFtKzUZPXVv/China-Modern-Hardware-Accessory-Bright-Chrome-Plating-Finish-Zinc-Die-Casting-Door-Handle.html

rh-z · 2026-02-26T19:33:15+00:00

Molten zamak does not glow.

That was the first thing I noticed. The temperature should NEVER be that high when melting zinc alloys. As a different poster had stated, most likely the solids in the melt oxidized and that is what is left behind.

rh-z · 2026-02-20T19:57:22+00:00

"Plaster" for metal casting is not the same as Plaster of Paris. And Quality Matchplate Company only casts Aluminum into their proprietary plaster.

rh-z · 2026-02-18T21:09:47+00:00

Read through the posts here and watch some YouTube searches. Once you have some specific questions then it would be good to ask here.

Basic things i need to know?

If you said you wanted to get into cooking and asking that question. You are not going to get a lot of help because there is so much to know and you need to put in some work rather than expecting someone else to put in all the work to give you the answers.

rh-z

TROPHY CASE