BK

Bruce Kaatz

30/03/2015 12:31 AM

HDPE surface attachment

A little background before my question. A few years back I built a 4X8
outfeed table around my Uni. Top was a sheet of 3/4" MDF with a few coats
of varnish. Worked well as an assembly bench and outfeed table, with the
saw in the lefthand corner.
Bearings went out on the Uni and I had to tear apart the outfeed table to
get at the Uni guts. Lets just say the glued and screwed MDF top doesn't
look as good now as it did a week ago.
Starting the re-assembly of the saw and I'm planning the outfeed table (aka
assembly bench). Planning on a sheet good top. Last evening I found a
1/4" sheet of HDPE in black with a slick smooth side and a slightly
textured reverse side (not rough, more like a textured formicia). Think it
would make a great surface. I want to be able to remove it for the next
time I need to replace bearings, and here comes the question.
Does anyone have any experience with attaching HDPE to a large flat
surface? I'm thinking of screws with a countersink...but would appreciate
your suggestions and thoughts.


This topic has 13 replies

JG

Joe Gwinn

in reply to Bruce Kaatz on 30/03/2015 12:31 AM

31/03/2015 10:15 AM

In article <[email protected]>, Unquestionably Confused
<[email protected]> wrote:

> On 3/30/2015 8:55 AM, BenignBodger wrote:
> > On 3/29/2015 8:31 PM, Bruce Kaatz wrote:
> >> A little background before my question. A few years back I built a 4X8
> >> outfeed table around my Uni. Top was a sheet of 3/4" MDF with a few
> >> coats
> >> of varnish. Worked well as an assembly bench and outfeed table, with the
>
> [snip]
>
> >> Think it
> >> would make a great surface. I want to be able to remove it for the next
> >> time I need to replace bearings, and here comes the question.
> >> Does anyone have any experience with attaching HDPE to a large flat
> >> surface? I'm thinking of screws with a countersink...but would
> >> appreciate
> >> your suggestions and thoughts.
> >>
> >
> > I've never done large sheets of HDPE but for runners and such I've
> > always found that carefully countersunk machine screws work well. I
> > wonder if there could be problems with expansion and contraction rates
> > between the substrate and the plastic. Like I say, I've never used HDPE
> > in big enough chunks for that to matter.
>
> Sounds like a plan. To preserve the "removability" you don't have too
> many options.
>
> Not sure that I'd worry too much about the expansion/contraction.
> Assuming his substrate is plywood or some other dimensionally stable
> material he should be good. As insurance, I'd make the holes slightly
> oversized or... maybe stick with the count sinking but elongate them
> and use a pan head screw that would allow for some movement all around.

The plywood responds to humidity, while the HDPE does not, so buckling
is likely in some seasons. I'd use flat head machine screws the go
through an oversize hole in the plywood, with a fender washer and pair
of nuts on the underside of the plywood. This will allow sliding to
take up relative growth while keeping the HDPE flat. Do not
overtighten. Having two nuts on the same screw allows the nuts to be
tightened against one another without compressing the wood. You may
need some screws in the middle of the HDPE sheet, as these often come
with some curl.

Joe Gwinn

LH

"Lew Hodgett"

in reply to Bruce Kaatz on 30/03/2015 12:31 AM

29/03/2015 6:19 PM


"Bruce Kaatz" wrote:

> Last evening I found a
> 1/4" sheet of HDPE in black with a slick smooth side and a slightly
> textured reverse side (not rough, more like a textured formicia).
> Think it
> would make a great surface. I want to be able to remove it for the
> next
> time I need to replace bearings, and here comes the question.
> Does anyone have any experience with attaching HDPE to a large flat
> surface? I'm thinking of screws with a countersink...but would
> appreciate
> your suggestions and thoughts.
------------------------------------------------------------------------
Trap the HDPE sheet with fiddles to the 3/4" top material, then attach
HDPE with #10-24 flat head stove bolts.

The fiddles trap the HDPE sheet preventing horizontal movement while
the stove bolts keep the HDPE sheet in place without overloading
flat head bolt connection.

When it is time to replace, simply unbolt it to remove.

Lew

Pp

Puckdropper

in reply to Bruce Kaatz on 30/03/2015 12:31 AM

30/03/2015 1:22 AM

"Lew Hodgett" <[email protected]> wrote in news:5518a4a8$0$46468
[email protected]:

>
> "Bruce Kaatz" wrote:
>
>> Last evening I found a
>> 1/4" sheet of HDPE in black with a slick smooth side and a slightly
>> textured reverse side (not rough, more like a textured formicia).
>> Think it
>> would make a great surface. I want to be able to remove it for the
>> next
>> time I need to replace bearings, and here comes the question.
>> Does anyone have any experience with attaching HDPE to a large flat
>> surface? I'm thinking of screws with a countersink...but would
>> appreciate
>> your suggestions and thoughts.
> -----------------------------------------------------------------------
>
> Trap the HDPE sheet with fiddles to the 3/4" top material, then attach
> HDPE with #10-24 flat head stove bolts.
>
> The fiddles trap the HDPE sheet preventing horizontal movement while
> the stove bolts keep the HDPE sheet in place without overloading
> flat head bolt connection.
>
> When it is time to replace, simply unbolt it to remove.
>
> Lew

What's a fiddle?

Puckdropper
--
Make it to fit, don't make it fit.

LH

"Lew Hodgett"

in reply to Bruce Kaatz on 30/03/2015 12:31 AM

29/03/2015 6:54 PM


"Puckdropper" wrote:

>What's a fiddle?

-----------------------------------------------------------
Nautical. a small ledge or barrier raised in heavy weather to keep
dishes,
pots, utensils, etc., from sliding off tables and stoves.
---------------------------------------------------------
A nautical term as defined above.

In this application, a fiddle would be a wood strips
1/4"-1/2" thick x 1" min wide x 18" long.

Strips are attached to 3/4" top face with screws with 1/4" of the
fiddle raised above the 3/4" top surface trapping the HDPE.

Lew



LH

"Lew Hodgett"

in reply to Bruce Kaatz on 30/03/2015 12:31 AM

30/03/2015 5:37 PM


"dadiOH" wrote:

> 1/4" above the PLY, inside edge beveled, the other material edge
> beveled to fit under.
>
> What I don't understand is the necessity for it if the material is
> going to be screwed/bolted to the ply.
----------------------------------------------------------------
Strictly belt & suspenders.

Bolt the leading edge of the HDPE to insure that there can be no hang
up of the material being fed thru saw.

Depending on how you design it, the bolts can also serve to hold the
fiddles in place.

Lew

JM

John McCoy

in reply to Bruce Kaatz on 30/03/2015 12:31 AM

30/03/2015 5:02 PM

"Lew Hodgett" <[email protected]> wrote in news:5518acf4$0$46428
[email protected]:

> -----------------------------------------------------------
> Nautical. a small ledge or barrier raised in heavy weather to keep
> dishes,
> pots, utensils, etc., from sliding off tables and stoves.
> ---------------------------------------------------------
> A nautical term as defined above.
>
> In this application, a fiddle would be a wood strips
> 1/4"-1/2" thick x 1" min wide x 18" long.
>
> Strips are attached to 3/4" top face with screws with 1/4" of the
> fiddle raised above the 3/4" top surface trapping the HDPE.
>

Not sure how well that would work for the OP's intention
of using it as an outfeed table and assembly table. Seems
like you wouldn't want any projections, not even 1/4".

John

BK

Bruce Kaatz

in reply to Bruce Kaatz on 30/03/2015 12:31 AM

30/03/2015 11:41 PM

> Sounds like a plan. To preserve the "removability" you don't have too
> many options.
>
> Not sure that I'd worry too much about the expansion/contraction.
> Assuming his substrate is plywood or some other dimensionally stable
> material he should be good. As insurance, I'd make the holes slightly
> oversized or... maybe stick with the count sinking but elongate them
> and use a pan head screw that would allow for some movement all
> around.

Thanks for the suggestions. I'm thinking the stove bolts will work fine to
hold the HDPE in place. Maybe a maple edge around to go with the fiddle
concept. And I hope you are right Leon about not needing another set of
bearings. It isn't a bad job replacing them, but not something I want to
do very often.
Thanks for the help with my project. It is appreciated.

JM

John McCoy

in reply to Bruce Kaatz on 30/03/2015 12:31 AM

31/03/2015 1:19 AM

"dadiOH" <[email protected]> wrote in news:[email protected]:

> 1/4" above the PLY, inside edge beveled, the other material edge
> beveled to fit under.

Ah, got it. I had missed that the HDPE was also 1/4" thick.
Now I see what Lew was envisioning.

John

EP

Ed Pawlowski

in reply to Bruce Kaatz on 30/03/2015 12:31 AM

29/03/2015 9:17 PM

On 3/29/2015 8:31 PM, Bruce Kaatz wrote:

> Last evening I found a
> 1/4" sheet of HDPE in black with a slick smooth side and a slightly
> textured reverse side (not rough, more like a textured formicia). Think it
> would make a great surface. I want to be able to remove it for the next
> time I need to replace bearings, and here comes the question.
> Does anyone have any experience with attaching HDPE to a large flat
> surface? I'm thinking of screws with a countersink...but would appreciate
> your suggestions and thoughts.
>

Probably the best method. Adhesives don't hold it.

Ll

Leon

in reply to Bruce Kaatz on 30/03/2015 12:31 AM

29/03/2015 9:46 PM

On 3/29/2015 7:31 PM, Bruce Kaatz wrote:
> A little background before my question. A few years back I built a 4X8
> outfeed table around my Uni. Top was a sheet of 3/4" MDF with a few coats
> of varnish. Worked well as an assembly bench and outfeed table, with the
> saw in the lefthand corner.
> Bearings went out on the Uni and I had to tear apart the outfeed table to
> get at the Uni guts. Lets just say the glued and screwed MDF top doesn't
> look as good now as it did a week ago.
> Starting the re-assembly of the saw and I'm planning the outfeed table (aka
> assembly bench). Planning on a sheet good top. Last evening I found a
> 1/4" sheet of HDPE in black with a slick smooth side and a slightly
> textured reverse side (not rough, more like a textured formicia). Think it
> would make a great surface. I want to be able to remove it for the next
> time I need to replace bearings, and here comes the question.
> Does anyone have any experience with attaching HDPE to a large flat
> surface? I'm thinking of screws with a countersink...but would appreciate
> your suggestions and thoughts.
>


I'm thinking, go back with the same if you liked it. I really don't
think you will be replacing bearings again. These saws were built to
last more than a life time for anything much less than commercial use.

Bn

BenignBodger

in reply to Bruce Kaatz on 30/03/2015 12:31 AM

30/03/2015 9:55 AM

On 3/29/2015 8:31 PM, Bruce Kaatz wrote:
> A little background before my question. A few years back I built a 4X8
> outfeed table around my Uni. Top was a sheet of 3/4" MDF with a few coats
> of varnish. Worked well as an assembly bench and outfeed table, with the
> saw in the lefthand corner.
> Bearings went out on the Uni and I had to tear apart the outfeed table to
> get at the Uni guts. Lets just say the glued and screwed MDF top doesn't
> look as good now as it did a week ago.
> Starting the re-assembly of the saw and I'm planning the outfeed table (aka
> assembly bench). Planning on a sheet good top. Last evening I found a
> 1/4" sheet of HDPE in black with a slick smooth side and a slightly
> textured reverse side (not rough, more like a textured formicia). Think it
> would make a great surface. I want to be able to remove it for the next
> time I need to replace bearings, and here comes the question.
> Does anyone have any experience with attaching HDPE to a large flat
> surface? I'm thinking of screws with a countersink...but would appreciate
> your suggestions and thoughts.
>

I've never done large sheets of HDPE but for runners and such I've always
found that carefully countersunk machine screws work well. I wonder if
there could be problems with expansion and contraction rates between the
substrate and the plastic. Like I say, I've never used HDPE in big enough
chunks for that to matter.

dd

"dadiOH"

in reply to Bruce Kaatz on 30/03/2015 12:31 AM

30/03/2015 1:18 PM

John McCoy wrote:
> "Lew Hodgett" <[email protected]> wrote in news:5518acf4$0$46428
> [email protected]:
>
>> -----------------------------------------------------------
>> Nautical. a small ledge or barrier raised in heavy weather to keep
>> dishes,
>> pots, utensils, etc., from sliding off tables and stoves.
>> ---------------------------------------------------------
>> A nautical term as defined above.
>>
>> In this application, a fiddle would be a wood strips
>> 1/4"-1/2" thick x 1" min wide x 18" long.
>>
>> Strips are attached to 3/4" top face with screws with 1/4" of the
>> fiddle raised above the 3/4" top surface trapping the HDPE.
>>
>
> Not sure how well that would work for the OP's intention
> of using it as an outfeed table and assembly table. Seems
> like you wouldn't want any projections, not even 1/4".

1/4" above the PLY, inside edge beveled, the other material edge beveled to
fit under.

What I don't understand is the necessity for it if the material is going to
be screwed/bolted to the ply.

--

dadiOH
____________________________

Winters getting colder? Tired of the rat race?
Taxes out of hand? Maybe just ready for a change?
Check it out... http://www.floridaloghouse.net




UC

Unquestionably Confused

in reply to Bruce Kaatz on 30/03/2015 12:31 AM

30/03/2015 9:46 AM

On 3/30/2015 8:55 AM, BenignBodger wrote:
> On 3/29/2015 8:31 PM, Bruce Kaatz wrote:
>> A little background before my question. A few years back I built a 4X8
>> outfeed table around my Uni. Top was a sheet of 3/4" MDF with a few
>> coats
>> of varnish. Worked well as an assembly bench and outfeed table, with the

[snip]

>> Think it
>> would make a great surface. I want to be able to remove it for the next
>> time I need to replace bearings, and here comes the question.
>> Does anyone have any experience with attaching HDPE to a large flat
>> surface? I'm thinking of screws with a countersink...but would
>> appreciate
>> your suggestions and thoughts.
>>
>
> I've never done large sheets of HDPE but for runners and such I've
> always found that carefully countersunk machine screws work well. I
> wonder if there could be problems with expansion and contraction rates
> between the substrate and the plastic. Like I say, I've never used HDPE
> in big enough chunks for that to matter.

Sounds like a plan. To preserve the "removability" you don't have too
many options.

Not sure that I'd worry too much about the expansion/contraction.
Assuming his substrate is plywood or some other dimensionally stable
material he should be good. As insurance, I'd make the holes slightly
oversized or... maybe stick with the count sinking but elongate them
and use a pan head screw that would allow for some movement all around.



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