Note: In order to avoid wasting your time, please be advised that
welding is not currently an option here. Thanks for your
understanding.

I like these skates a lot, planning to make slight variations.

http://www.flickr.com/photos/27532210@N04/2565924423/

The aluminum flat bar is 1/16" thick from McMaster. Seems springier
than Lowe's aluminum and apparently harder so it doesn't clog my
tools.

After sanding the sides of the skate frame and the wheel fork (the two
aluminum flat bar pieces), the pieces are coated and Super glued
together. The wheel ends up precisely aligned.

The skates are taking a beating, that's what they're for. Most of the
forces are shearing type. Twisting pressure is handled by the
flexibility of the frame. I have high confidence in the bond,
otherwise I wouldn't be skating on them (away from cars and with lots
of protective gear). At the same time, I would like to provide a
better backup fastening than the single cheap screw currently being
used.

I would ask about screw placement, but that's probably a fine detail
that I should determine here. The current single screw is where I
think the bond is most likely to fail. I'll probably use more screws.

Again, the aluminum flat bar is 1/16" thick.
The skate frame thickness is somewhere between 1/16 and 1/8". I don't
know exactly, but I think it's a pretty hard alloy of some type.

Which of these McMaster machine screws would be most nearly
acceptable?

.... 6-32 or 8-32 Thread

.... Black-Oxide Fnsh Pan Head Phil 18-8 SS

.... 300 SS Pan Head Phil, specifications met... FF-S-92, QQ-P-35, MIL
51957, and passivated

Is there a matching nut for a rated screw like that? How important is
a nut on the other side of the threaded hole? I'll probably use
superglue to secure the screw.

Thank you.

If you are trying to resist shear forces, you want the screw as large as
possible in diameter and you want to avoid having the threaded portion
in contact with the plates in shear.

The bolt strength is not going to be terribly important, the aluminum
has a unknown strength but certainly less than half that of the bolt.

My first choice would be a socket head cap screw in black phosphate
finish but all of those are fully threaded until you get to over an inch
long.

Using a locking nut (Nylock) would be a good idea in this high vibration
application.

You didn't ask but I would be looking at using a fairly high strength
aluminum like 6061-T6 rather some no name, no grade wimpy stuff from the
hardware store.

John Doe wrote:
Note: In order to avoid wasting your time, please be advised that
welding is not currently an option here. Thanks for your
understanding.

I like these skates a lot, planning to make slight variations.

http://www.flickr.com/photos/27532210@N04/2565924423/

The aluminum flat bar is 1/16" thick from McMaster. Seems springier
than Lowe's aluminum and apparently harder so it doesn't clog my
tools.

After sanding the sides of the skate frame and the wheel fork (the two
aluminum flat bar pieces), the pieces are coated and Super glued
together. The wheel ends up precisely aligned.

The skates are taking a beating, that's what they're for. Most of the
forces are shearing type. Twisting pressure is handled by the
flexibility of the frame. I have high confidence in the bond,
otherwise I wouldn't be skating on them (away from cars and with lots
of protective gear). At the same time, I would like to provide a
better backup fastening than the single cheap screw currently being
used.

I would ask about screw placement, but that's probably a fine detail
that I should determine here. The current single screw is where I
think the bond is most likely to fail. I'll probably use more screws.

Again, the aluminum flat bar is 1/16" thick.
The skate frame thickness is somewhere between 1/16 and 1/8". I don't
know exactly, but I think it's a pretty hard alloy of some type.

Which of these McMaster machine screws would be most nearly
acceptable?

... 6-32 or 8-32 Thread

... Black-Oxide Fnsh Pan Head Phil 18-8 SS

... 300 SS Pan Head Phil, specifications met... FF-S-92, QQ-P-35, MIL
51957, and passivated

Is there a matching nut for a rated screw like that? How important is
a nut on the other side of the threaded hole? I'll probably use
superglue to secure the screw.

Thank you.

John Doe wrote:
Note: In order to avoid wasting your time, please be advised that
welding is not currently an option here. Thanks for your
understanding.

I like these skates a lot, planning to make slight variations.

http://www.flickr.com/photos/27532210@N04/2565924423/

The aluminum flat bar is 1/16" thick from McMaster. Seems springier
than Lowe's aluminum and apparently harder so it doesn't clog my
tools.
snip

Looking at the picture I would toss the aluminum your using. Get some
wider material and make a longer piece that can go along the sides of
the current frame and catch at least one of the existing wheel bolts.
Maybe even use sheet stock and bend it so that it can use the toe area
on the shoe as a brace.

Then on the nose area that you have one screw I would add a second. One
closer to the top and bottom to spread the clamping across the part.
That would give you three total hard connection points. Screw wise I
would use stainless 10-32 and short rivnuts.


I would toss the Super Glue. Get some GOOD epoxy and use that. With
the understanding that the failures you will likely see at the bonded
areas will likely be from aluminum oxide forming under the glue.

Or you could just go buy a pair of the inlines that are sold for off
road use.
http://1800wwsports.stores.yahoo.net/rolcoyoffroa.html
Rollerblade Coyote

--
Steve W.

"Steve W." wrote:

John Doe wrote:

I like these skates a lot, planning to make slight variations.

http://www.flickr.com/photos/27532210@N04/2565924423/

The aluminum flat bar is 1/16" thick from McMaster. Seems
springier than Lowe's aluminum and apparently harder so it
doesn't clog my tools.

Looking at the picture I would toss the aluminum your using. Get
some wider material and make a longer piece that can go along the
sides of the current frame and catch at least one of the existing
wheel bolts. Maybe even use sheet stock and bend it so that it can
use the toe area on the shoe as a brace.

Yup yup, good thoughts IMO.

Then on the nose area that you have one screw I would add a
second. One closer to the top and bottom to spread the clamping
across the part. That would give you three total hard connection
points. Screw wise I would use stainless 10-32 and short rivnuts.


I would toss the Super Glue. Get some GOOD epoxy and use that.

Like what, specifically?

With
the understanding that the failures you will likely see at the
bonded areas will likely be from aluminum oxide forming under the
glue.

Or you could just go buy a pair of the inlines that are sold for
off road use.
http://1800wwsports.stores.yahoo.net/rolcoyoffroa.html
Rollerblade Coyote

I'm very familiar with those and other off-road in-line skates. The
Coyotes were a chore to push with, the pneumatic wheels made them
very slow for anything but going downhill. There are others, but
nothing that resembles the function of mine for rough street
skating. I've used 100mm wheel speed skates. Mine are for speed
(hard wheels), stability (low profile), and handling bumps (big
front wheel). I'm still working on putting a stopgap between at
least the first and second wheels, that's what my earlier question
about Delrin was for.

Problem with the stopgap is that it needs to absorb shock without
moving into the wheels. That's a really tough qualification. I think
it's going to be a breakaway type, so that if I hit an extremely hard
object with lots of force, it will absorb some of the shock by
shattering, then it will be replaced. It would need to be replaced
periodically anyway.

RoyJ wrote:

If you are trying to resist shear forces,

I expect the glue to resist the shear forces. The screws are only
(hopefully) to temporarily keep the thing from flying apart if the
glue fails. Then everything would be remade.

you want the screw as large as
possible in diameter and you want to avoid having the threaded
portion in contact with the plates in shear.

Yes, that sounds desirable, however unlikely.

The bolt strength is not going to be terribly important, the
aluminum has a unknown strength but certainly less than half that
of the bolt.

My first choice would be a socket head cap screw in black
phosphate finish but all of those are fully threaded until you get
to over an inch long.

Using a locking nut (Nylock) would be a good idea in this high
vibration application.

You didn't ask but I would be looking at using a fairly high
strength aluminum like 6061-T6

Yeah, it's general-purpose 6060 or 6061 from McMaster. Once I know
what's needed, I would consider going for better aluminum.

On Jun 26, 2:11*pm, John Doe wrote:
"Steve W." wrote:
John Doe wrote:
I like these skates a lot, planning to make slight variations.

http://www.flickr.com/photos/27532210@N04/2565924423/

The aluminum flat bar is 1/16" thick from McMaster. Seems
springier than Lowe's aluminum and apparently harder so it
doesn't clog my tools.
Looking at the picture I would toss the aluminum your using. Get
some wider material and make a longer piece that can go along the
sides of the current frame and catch at least one of the existing
wheel bolts. Maybe even use sheet stock and bend it so that it can
use the toe area on the shoe as a brace.

Yup yup, good thoughts IMO.

Then on the nose area that you have one screw I would add a
second. One closer to the top and bottom to spread the clamping
across the part. That would give you three total hard connection
points. Screw wise I would use stainless 10-32 and short rivnuts.

* I would toss the Super Glue. Get some GOOD epoxy and use that.

Like what, specifically?

* With
the understanding that the failures you will likely see at the
bonded areas will likely be from aluminum oxide forming under the
glue.

Or you could just go buy a pair of the inlines that are sold for
off road use.
http://1800wwsports.stores.yahoo.net/rolcoyoffroa.html
Rollerblade Coyote

I'm very familiar with those and other off-road in-line skates. The
Coyotes were a chore to push with, the pneumatic wheels made them
very slow for anything but going downhill. There are others, but
nothing that resembles the function of mine for rough street
skating. I've used 100mm wheel speed skates. Mine are for speed
(hard wheels), stability (low profile), and handling bumps (big
front wheel). I'm still working on putting a stopgap between at
least the first and second wheels, that's what my earlier question
about Delrin was for.

Problem with the stopgap is that it needs to absorb shock without
moving into the wheels. That's a really tough qualification. I think
it's going to be a breakaway type, so that if I hit an extremely hard
object with lots of force, it will absorb some of the shock by
shattering, then it will be replaced. It would need to be replaced
periodically anyway.

I like your idea allot. But I agree super glue is wrong for this.
Epoxy is probably good. You should look at 3M or Duro to find out
which one. Sanding it wetted with the epoxy is a good idea. I actually
like the two mounting points with one being the second axle (first
small wheel) the best and epoxy bonding to take most of the load off
that little screw up front.
Excellent idea though.
Karl

" wrote:

Excellent idea though.

wow, thanks

John Doe wrote:
"Steve W." wrote:

John Doe wrote:

I like these skates a lot, planning to make slight variations.

http://www.flickr.com/photos/27532210@N04/2565924423/

The aluminum flat bar is 1/16" thick from McMaster. Seems
springier than Lowe's aluminum and apparently harder so it
doesn't clog my tools.

Looking at the picture I would toss the aluminum your using. Get
some wider material and make a longer piece that can go along the
sides of the current frame and catch at least one of the existing
wheel bolts. Maybe even use sheet stock and bend it so that it can
use the toe area on the shoe as a brace.

Yup yup, good thoughts IMO.

Then on the nose area that you have one screw I would add a
second. One closer to the top and bottom to spread the clamping
across the part. That would give you three total hard connection
points. Screw wise I would use stainless 10-32 and short rivnuts.


I would toss the Super Glue. Get some GOOD epoxy and use that.

Like what, specifically?

Maybe some Devcon or one of the 3M family. NOT a 5 minute type, you want
a longer stronger cure. You would need to look over some of them for
bonding abilities. I use a few different types but don't bond aluminum much.
I would also do a dry sanding to remove the coatings, then use a finer
grit wet paper, whetted with the epoxy just prior to assembly. That
would give you the best bond.



With
the understanding that the failures you will likely see at the
bonded areas will likely be from aluminum oxide forming under the
glue.



I'm very familiar with those and other off-road in-line skates. The
Coyotes were a chore to push with, the pneumatic wheels made them
very slow for anything but going downhill. There are others, but
nothing that resembles the function of mine for rough street
skating. I've used 100mm wheel speed skates. Mine are for speed
(hard wheels), stability (low profile), and handling bumps (big
front wheel). I'm still working on putting a stopgap between at
least the first and second wheels, that's what my earlier question
about Delrin was for.

Problem with the stopgap is that it needs to absorb shock without
moving into the wheels. That's a really tough qualification. I think
it's going to be a breakaway type, so that if I hit an extremely hard
object with lots of force, it will absorb some of the shock by
shattering, then it will be replaced. It would need to be replaced
periodically anyway.


carbon fiber reinforced resin? Or maybe some light aluminum with molded
delrin material over it? How about machining them out of the molded
rubber they make hockey pucks from?


--
Steve W.

1/16" bar seems awfully light for that - think I'd go with 1/8" at
least. While the bar is quite strong in the wide direction, a little
side force and it will twist or bend. I'd also extend it back along
the frame for a couple of the axle screws - get longer ones and use
them to hold the bar on as well.

It may be the perspective, but that big wheel seems as though it might
rub on the boot. I don't know a thing about those skates, but wonder
if it might make sense to make that wheel higher than the others?
That way, it wouldn't interfere with normal skating but would still
guide the skates up and over obstacles when you hit them.

6-32 and 8-32 screws seem way too light. I'd use 10 or 12. The skate
frame may be adequate to hold the threads, but I'd probably use nuts
as well. They are readily available. Loctite on the threads will
keep them tight.

John Martin

I know you're asking for screws, but have you ever considered using rivets
as a better alternative?


"John Doe" wrote in message
...
|
| Note: In order to avoid wasting your time, please be advised that
| welding is not currently an option here. Thanks for your
| understanding.
|
| I like these skates a lot, planning to make slight variations.
|
| http://www.flickr.com/photos/27532210@N04/2565924423/
|
| The aluminum flat bar is 1/16" thick from McMaster. Seems springier
| than Lowe's aluminum and apparently harder so it doesn't clog my
| tools.
|
| After sanding the sides of the skate frame and the wheel fork (the two
| aluminum flat bar pieces), the pieces are coated and Super glued
| together. The wheel ends up precisely aligned.
|
| The skates are taking a beating, that's what they're for. Most of the
| forces are shearing type. Twisting pressure is handled by the
| flexibility of the frame. I have high confidence in the bond,
| otherwise I wouldn't be skating on them (away from cars and with lots
| of protective gear). At the same time, I would like to provide a
| better backup fastening than the single cheap screw currently being
| used.
|
| I would ask about screw placement, but that's probably a fine detail
| that I should determine here. The current single screw is where I
| think the bond is most likely to fail. I'll probably use more screws.
|
| Again, the aluminum flat bar is 1/16" thick.
| The skate frame thickness is somewhere between 1/16 and 1/8". I don't
| know exactly, but I think it's a pretty hard alloy of some type.
|
| Which of these McMaster machine screws would be most nearly
| acceptable?
|
| ... 6-32 or 8-32 Thread
|
| ... Black-Oxide Fnsh Pan Head Phil 18-8 SS
|
| ... 300 SS Pan Head Phil, specifications met... FF-S-92, QQ-P-35, MIL
| 51957, and passivated
|
| Is there a matching nut for a rated screw like that? How important is
| a nut on the other side of the threaded hole? I'll probably use
| superglue to secure the screw.
|
| Thank you.
|
|
|
|
|

John Martin wrote:

It may be the perspective, but that big wheel seems as though it
might rub on the boot.

At idle, there is a tiny clearance between the wheel and the boot. I
was considering sanding/filing a notch in the very thick plastic
boot, but the wheel made a smooth notch by itself. I guess the metal
flexes upwards too.

I don't know a thing about those skates, but wonder if it might
make sense to make that wheel higher than the others?

That was my first plan, thinking it would further increase the
obstacle surmounting capability of the front end. A competing
concern is that the main benefit of an in-line skate with at least
three wheels (on the street) is its ability to span small potholes
without the front or rear wheel dropping into the hole. The current
same-level placement helps the small second wheel roll over
obstacles.

For what it's worth, the design complexities of in-line skate wheel
size/hardness/placement are more than meets the mortal eye. Much
fun.

That way, it wouldn't interfere with normal skating but would
still guide the skates up and over obstacles when you hit them.

I did 9 miles this morning. Seems okay so far. Street skating isn't
normal anyways.


Thanks to all of the replies.

On Jun 27, 6:19*am, John Doe wrote:
" wrote:
Excellent idea though.

wow, thanks

If you'd ever seen me on roller blades and seen the bike path I was
learning on you'd know why I like it.
You're welcome.
Karl

You might want to consider shoulder screws (bolts) for attaching the wheel
plates to the skate frame. The shoulder section eliminates having any
threads in the shear area. A suitable washer and nut should/would probably
be better than threading a fastener into thin sheet material.
Using 2 per plate would not require any adhesive.

There are numerous styles available, and types with low-profile heads are
commonly available (less likely to get snagged by some passing object).

WB
..........
metalworking projects
www.kwagmire.com/metal_proj.html


"John Doe" wrote in message
...

Note: In order to avoid wasting your time, please be advised that
welding is not currently an option here. Thanks for your
understanding.

I like these skates a lot, planning to make slight variations.

http://www.flickr.com/photos/27532210@N04/2565924423/

The aluminum flat bar is 1/16" thick from McMaster. Seems springier
than Lowe's aluminum and apparently harder so it doesn't clog my
tools.

After sanding the sides of the skate frame and the wheel fork (the two
aluminum flat bar pieces), the pieces are coated and Super glued
together. The wheel ends up precisely aligned.

The skates are taking a beating, that's what they're for. Most of the
forces are shearing type. Twisting pressure is handled by the
flexibility of the frame. I have high confidence in the bond,
otherwise I wouldn't be skating on them (away from cars and with lots
of protective gear). At the same time, I would like to provide a
better backup fastening than the single cheap screw currently being
used.

I would ask about screw placement, but that's probably a fine detail
that I should determine here. The current single screw is where I
think the bond is most likely to fail. I'll probably use more screws.

Again, the aluminum flat bar is 1/16" thick.
The skate frame thickness is somewhere between 1/16 and 1/8". I don't
know exactly, but I think it's a pretty hard alloy of some type.

Which of these McMaster machine screws would be most nearly
acceptable?

... 6-32 or 8-32 Thread

... Black-Oxide Fnsh Pan Head Phil 18-8 SS

... 300 SS Pan Head Phil, specifications met... FF-S-92, QQ-P-35, MIL
51957, and passivated

Is there a matching nut for a rated screw like that? How important is
a nut on the other side of the threaded hole? I'll probably use
superglue to secure the screw.

Thank you.

You have several issues from what I can see. Use button head screws,
a good fastener house will carry them. Your main point of weakness is
at the screw location where the torsion will cause stress fractures
and weaken the the aluminum. Try to find scrap anodized aluminum and
cut out a piece from that. Aluminum will corrode when not anodized. It
makes a salt on its surface and will eventually reject the glue and
corrode around the fastener from the uneven charges.
I would consider a piece of titanium for the plate. Just search on
Ebay for titanium sheet, it is MUCH stronger than aluminum and highly
corrosion resistant especially for the salts and organics that come
from the roadway. It is strong as steel with less than 60% of its
density. Search for titanium sheet on Ebay, enter 310062160956 into
the search field, it looks like a likely candidate. It is .107" thick
which is very strong, which you need as the bending forces on this
larger wheel is much higher than the smaller wheels.
Think triangle on the bar design. The racking on the frame will
crack it over time if twists too much so take the support further back
in the frame. Airplanes suffer from this and they only bend a little
compared to the twist forces in your current set up. I would secure
it in three or four points. Screws top and bottom in the gaps between
where the wheels meet and two out on the tip of the frame. This will
stiffen the frame considerably.
You need a good safety factor on a design like this. If you are
going down the road and hit something, it could cause a bend on a
stress fracture, which in turn allows the wheel to contact the
frame....oops. So a light design that works today, may be a disaster
tomorrow.