Belt sander build vote

[rabler]

re: FreeCAD. There are experts who use both Fusion 360 and FreeCAD together, and some who have migrated to FreeCAD. Given that Fusion 360 is moving to a yearly update/verify model, I will stay with FreeCAD. It's the only way I know I will never be stuck with a load of invested designs, and a tool I can only access on new terms. In practice, I find there are tutorials on YouTube that take you to the point you start getting along with it just fine.

Yeah, the idea that these yearly licensed software products can change the rules whenever their profit margin would benefit does not leave me with lots of confidence in them. I remember when Adobe's licensed PDF tools "updated" and suddenly OCR was no longer supported, it became a new product for significant $$. Professionally I used a lot of open source tools so that was a plus in my mind for FreeCad.

 

[rabler]

Here's what I've done so far in freecad for mine: Pretty simple ..

 

[graham-xrf]

Good looking build! I only have a 120V MIG welder and also end up bolting where others would weld. I'm not a very good welder! Is 2 HP necessary? Never short on power that way.

1 HP is 746 Watts. You need a bit more for this job! 1 HP is OK, but consider 1.5 HP

Another thing is the 120V. USA homes normally have two power line phases, at 240V between them, but center-tapped to provide two 120V phases, and a common neutral. Using 240V for shop stuff is much the better way to do it, if you can get some 240V sockets in there, and try and use it for shop stuff, especially if you want to use VFDs.

The currents in 240V supply are half that of 120V. With only 120V, then 2HP, even at 100% efficiency (which you don't have) takes a whole 12.4 Amps, when it could be 6.2A. Circuit losses a four times as much compared to 240V circuits, and you need bigger fatter copper wires.
240V available for VFDs can make then lower cost, since they don't need semiconductors rated for double the current.

You need not dump all your 120V kit, just start using 240V when you can.

 

[rabler]

1 HP is 746 Watts. You need a bit more for this job! 1 HP is OK, but consider 1.5 HP

Another thing is the 120V. USA homes normally have two power line phases, at 240V between them, but center-tapped to provide two 120V phases, and a common neutral. Using 240V for shop stuff is much the better way to do it, if you can get some 240V sockets in there, and try and use it for shop stuff, especially if you want to use VFDs.

The currents in 240V supply are half that of 120V. With only 120V, then 2HP, even at 100% efficiency (which you don't have) takes a whole 12.4 Amps, when it could be 6.2A. Circuit losses a four times as much compared to 240V circuits, and you need bigger fatter copper wires.
240V available for VFDs can make then lower cost, since they don't need semiconductors rated for double the current.

You need not dump all your 120V kit, just start using 240V when you can.

While I agree in general with all of this, for 3phase motors under 1 HP I do like using the 120V VFDs such as the Teco L510 series. There is always going to be more 120V sockets than 240V in most U.S. hobby shops.

 

[graham-xrf]

@rabler :
I do so agree, which is why I said there was no need to attempt a grand changeover.
Usually, the 240V is a a bit special, only routed to stuff like cookers, or maybe higher other energy stuff. It probably needs that one has to run in a separate special 240V line to the shop, to a socket or two.

1 HP is probably OK for grinding. It may just take a bit longer, and maybe that's a good thing. Going fast with a big belt in a huge shower of sparks does make things real hot, and needs a surer touch to avoid mistakes.

 

[rabler]

@rabler :
I do so agree, which is why I said there was no need to attempt a grand changeover.
Usually, the 240V is a a bit special, only routed to stuff like cookers, or maybe higher other energy stuff. It probably needs that one has to run in a separate special 240V line to the shop, to a socket or two.

1 HP is probably OK for grinding. It may just take a bit longer, and maybe that's a good thing. Going fast with a big belt in a huge shower of sparks does make things real hot, and needs a surer touch to avoid mistakes.

I'm using 240V for the 2HP belt grinder. Even for 1HP, I'd lean toward 240V, and certainly for 1.5HP. Just that not all shop tools need even a full 1HP. I used the 120V VFD that produces a 240V output for the 1/4HP diamond lapper that I built.

One of the marginal issues with 240V in the US I've had an inspector insist that every 240V appliance needs it's very own circuit. I haven't dug through the NEC recently but I don't think that is true as long as they are general purpose plug in devices rather than hardwired. The inspector I was dealing with on that admitted to not being well versed on electrical code ... (it was in association with a final signoff on a barn I'd built).

For my new shop that should go up next month, I'm upgrading my home service from 200A to 400A service, so I'll have a separate 200A service disconnect for the new shop. I'll use a similar strategy as I wired my current shop (which will become woodworking only). Two 20A 240V circuits run receptacles placed as paired outlets every 8 feet, and 2 pairs in the ceiling near the center of the room. A 30A circuit with three drops, and two drops at 50A for welders. Plus dedicated 240V circuits for the AC, compressor, and dust collector. New shop will also include a 125A circuit for the RPC.

 

[mikey]

Regarding HP, my little 2x42 sander has a 1/2HP motor and with ceramic belts it will flat out eat up HSS. I cannot bog it down even with heavy pressure so for tool grinding, big HP is not necessary. However, if you are going to use it mainly for fabrication or knife grinding then I think 3/4-1HP would do okay but 1-1/2HP will do better. 2HP, in my opinion, is definitely overkill with the ready availability of modern belts. The motor I have for my new belt sander is a 1-1/2HP DC motor but I'm really thinking about going with a 3/4HP instead.

 

[mikey]

I doubt I will get this around here. Don't even know where to go and look for it. Silly question...is the platen the part where the belt runs against? If so,all I see is metal ones on YouTube.

Check ebay for parts.

The platen is the flat plate that backs the belt in the area where your work touches the belt so you have something to push against. If the platen is not flat then you cannot grind a flat surface.

I have not noted excessive wear on the steel platen.

I've seen several comments like this regarding the platens on the old grinders so I believe you. However, my own experience and that of many others suggests that steel platens on lesser grinders do wear, which is why glass platens are commonly seen on knife grinders. I don't think this matters for general fabrication or shop use but for tool grinding, which is the main reason for me having a belt sander, the platen must be dead flat or the geometry of the tool will be off and this matters to me. I only suggested a glass platen because it has proven itself to stay dead flat after grinding hundreds of HSS tools on it.

 

[addertooth]

Check ebay for parts.

The platen is the flat plate that backs the belt in the area where your work touches the belt so you have something to push against. If the platen is not flat then you cannot grind a flat surface.



I've seen several comments like this regarding the platens on the old grinders so I believe you. However, my own experience and that of many others suggests that steel platens on lesser grinders do wear, which is why glass platens are commonly seen on knife grinders. I don't think this matters for general fabrication or shop use but for tool grinding, which is the main reason for me having a belt sander, the platen must be dead flat or the geometry of the tool will be off and this matters to me. I only suggested a glass platen because it has proven itself to stay dead flat after grinding hundreds of HSS tools on it.

Yes, the Square Wheel belt sander I have was used by my father and me to make knives, back when he was a member of the American Knifemaker's Guild. It got very heavy use. It has the original 1 HP industrial 110/220v motor and had plenty of power to grind metal till it was glowing red hot. Obviously, when dealing with knifemaking steel, you didn't want to get it to cherry red, due to the risk of depleting the carbon in the metal, and work hardening. A water bucket was next to the grinder to dip the steel in to cool it after each couple of passes.

I was tickled pink when he called me to drive 1300 miles to come pick it up. I have a lot of history with that belt sander. It is worth noting the JET version of it now costs over 2000 dollars. It is still considered the gold standard for belt sanders for knife makers.

 

[mikey]

Yup, the Wilton Square Wheel was one of the first. One of my friends owned one and I got to use it. That is a beast of a grinder, very solid and powerful. If I ever had a chance at one, I would have jumped!