What to use to make new grilles?

[Charles218]

As I get close to completing the refurbishing of a couple of pair of 3A's, I need to construct new grilles. One pair has two broken grilles, while the other has no grilles. The best that I could find at Lowe's was something that they call "hardboard", at least I think that it what it is. They only have it in 1/8 inch thickness while the broken grilles that I have are 1/4 inch thick. I would like to see what others use when making grilles. Would plywood work? Is there a source for whatever material was used originally by AR?

[ra.ra]

Hi Charles.

Below (in blue) is a partial response to a recent thread about 2ax speakers, with an attachment from the 3a restoration guide. 1/8" thick material might be satisfactory for a very small speaker, but certainly not for a cabinet as large as the AR-3a - - - even my tiny AR-7's use a hardboard that is at least 3/16' thick, possibly 1/4". There may be a drawing in the Library with dimensions for the cut-outs for the drivers of a 3a, or someone may furnish you with this information.

For some reason (maybe availability of stock material?), one pair of beloved speakers in my stable, the Rectlinear Mini-III, has grille frames which are made from two separate pieces of 1/8" hardboard sandwiched together. This solution works just fine, but there is no sensible reason to pursue this as an option.

In your case, maybe you should look beyond Lowe's. When I lived in Ann Arbor, many of the experienced carpenters took their business to Fingerle Lumber, near Madison and Main, a few blocks north of the stadium.

From what I have seen, almost all of the grille frames from the classic AR's consist of 1/4" hardboard, more commonly known as Masonite. Some grilles from small early speakers (e.g. AR-4's) had frames made from 1/4" plywood or slats of softwood, but these are not nearly as robust as the more common Masonite frames. The cut-out openings in the frames always correlated with the size and placement of the drivers in the speaker cabinet.

1/4" masonite is manufactured in tempered and untempered versions. I believe tempered may have even a bit more resistance to moisture absorption and exhibits superior stiffness. Downside might be that it is more difficult to receive a staple for the grille cloth.

Attached is partial note from AR-3a restoration guide. If you have access to a Home Depot, I think they sell some 1/4" Masonite in small pre-cut sizes that may make the process a bit easier than lugging around a 4' x 8' sheet.

[xmas111]

ra.ra your advise is right on as usual.

Charles,

Do you have a Home Depot near by if so you can use this:http://www.homedepot.com/p/Unbranded-1-4-in-x-2-ft-x-4-ft-Hardboard-Tempered-7005017/202088798#.UtRBZE2d7mE

The only issue is it's really 3/16" thick not a 1/4" as advertised. I don't know if you find true 1/4" thick masonite any longer. Kind of like a 2" x 4" is only 1 1/2" x 3 1/2".

John

[JKent]

Hi Charles

Take a look at "Replacing the AR-3 Grilles" attached to Post #1 here http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=7436

You should be able to find 3/16" Masonite aka hardboard http://www.panel.com/uploads/whatisitcda0.pdf at a real (not big box) lumber yard if you have any near you. The 1/4" is quite hard to find but it is still available: http://www.menards.com/main/building-materials/panel-products/industrial-panels/hardboard-pegboard/1-4-4-x-8-tempered-hardboard/p-1986923-c-13340.htm

3/16" should be easy to find and is probably thick enough.

I don't know whether this Vintage AR offering is for one bare grille (which would be outrageously expensive IMHO) or for a pair but you might ask. His frames are 3/16" hardboard http://www.ebay.com/itm/ACOUSTIC-RESEARCH-AR-3a-NEW-BARE-SPEAKER-GRILLES-COVER-YOURSELF-/160664796310?pt=US_Speaker_Parts_Components&hash=item25685e3c96

Kent

oops--guess I was typing and finding links while ra answered your question.

I doubt that all Home Depots have the 1/4". At least the one near me does not. And I am strongly biased in favor of real local lumber yards. Sounds like ra had 2 good suggestions in your city.

[Charles218]

Well as always, thanks for the replies, this is all very helpful.

I had actually thought of the idea of putting two 1/8 sheets of hardboard together, and then tucking the edges of the grille cloth in between the two sheets. Having put new cloth on a few grilles before I know how difficult it can be to get it right, ending up without any sags and with nice straight lines of the fabric weave. I'm not sure that using two sheets would make it any easier.

As can be seen in the attached photo, the grille that was on the 3A is much lighter in color then Masonite and also much softer, making it easier to get staples to bite. Robert, I will try Fingerle's, they are a full-serve quality lumber yard and most likely to have something like this. I often defer to Lowe's as they are less then five minutes from my house, Home Depot is twenty-five minutes away.

My friend who built is own house, and has a table saw, air powered stapler, all of the big boy toys, etc., suggested using 1/4 inch plywood. That sounds like a good idea to me, is there a downside to using plywood? Once I get the proper material to use, he is going to do the cutting for me.

Thanks again for the help!!!

[dxho]

Masonite works better and holds staples well. Plywood, cut in roughly the shape of the original grill frame, breaks too easily.

The little hand-powered staplers, like the Arrow T-50 or T-55, work great.

[ra.ra]

The grille you've shown is indeed some type of hardboard, but maybe not quite the high-quality product as some other manufacturers may produce. Among my own AR grille frames, I have hardboard such as yours that has very ragged cut edges, but I also have other qualities of hardboard that exhibit very precise cut-outs. I also have one pair of 4x grilles that do use 1/4" plywood. This also seems to work just fine, but after the "cut-outs" are removed, it does not seem to exhibit quite the same degree of planar rigidity that the hardboard (masonite) frames do. This might be a concern with larger frames for the 3a.

It's always good to have a friend with all of the necessary big-boy tools, and you should make use of his willing assistance and then reward him with a bottle of his favorite drink. [Last month, in fact, I had to produce a full-scale foamcore mock up of a Noguchi table, and I'm thinking, "How do I cut that shape?" Turns out, I was able to get assistance from my good pal (who builds harpsichords) with a full shop and after a few tests, found the correct tool to make an accurate and smooth cut with an ever changing curvature. His compensation was a bottle of scotch.]

One last thought: although it is not a commonly available material, I have been able to procure 1/4" sheets of MDF (medium density fiberboard) which, at least in reasonably sized panels, is able to maintain a very high degree of stiffness. It is lighter in weight (and density) and lighter in color than hardboard, but it seems to accept staples more cooperatively than the bullet-proof tempered hardboard.

[Charles218]

I took ra.ra's advice, drove into town today and stopped at Fingerle Lumber, the family owned, full-service, been around since as long as I can remember, lumber yard. I should have started there, ignoring the fact that Lowe's is less then five minutes from my house. I was shown several different choices of 1/4 inch stock, along with the pro's and con's of each. When I was finished, I drove home with four "perfectly" sized pieces to use for my 3A's, plus enough extra material to make grilles for eight more cabinets in the future. I got the MDF, it is an actual 1/4 inch thick, appears to be very solid, and the test staples were fully seated, flush with the surface. Total cost, "priceless."

Thanks again for all of the input!!!

[ra.ra]

I am very pleased to hear this is working out several reasons:

a.) Fingerle's is still in business

b.) Customer service is not entirely dead.

c.) 1/4" MDF is available from non-specialty sources.

I had meant to include some images earlier in this discussion, but my little digi-cam was temporarily on the fritz. All better now, here's a few pics to illustrate this thread:

1. (3) AR-4x grilles, (1) AR-7 grille

2. left - 3/16" hardboard w/smooth back, clean cuts; right - 1/4" hardboard w/rough back, ragged cuts

3. left - softwood slats, glued and stapled; right - 1/4" plywood

4. left - (2) layers 1/8" hardboard (Rectilinear); right - 1/4" MDF panel

It's great to hear that the lumber yard offers this service to cut-to-size (sounds like maybe you had to purchase a full 4 x 8 sheet?), but the more challenging aspect is which tools/techniques to use to neatly create the driver cut-outs. A manufacturing facility would have all the necessary set-ups - - - drill press, hole saws, jigsaws, routers and jigs, etc. - - - so it will be interesting to see what your pal with the big-boy tools comes up with for a solution. Please keep us posted on this and other aspects of these restorations.

[Rwhitebbq]

i am interested in the big boy tools your friend uses to cut the grille openings. I now have three 1/4" MDF examples of what they should not look like ;-) as well as another $7 2x4' sheet from HD.

Looks like I'll be building a jig for use with a router, as "straight" just isn't straight after an attempt with a jigsaw and an OMT (oscillating multi tool).

[xmas111]

i am interested in the big boy tools your friend uses to cut the grille openings. I now have three 1/4" MDF examples of what they should not look like ;-) as well as another $7 2x4' sheet from HD.

Looks like I'll be building a jig for use with a router, as "straight" just isn't straight after an attempt with a jigsaw and an OMT (oscillating multi tool).

Rwhitebbq,

A jigsaw as you found out will never give nice straight cuts without some type of guide.... even then it's iffy at best.

Maybe if you have a local high school where they still have shop class or a votech, they may be willing to cut them for you if you have the dimensions. Else you're looking at a industrial size band saw with a T square and/or a router with a template and steady hand.

Good luck with them. Please show some pics when you complete them.

John

[ra.ra]

To the OP, Charles - - - if I'm not mistaken, you already have one finished pair of 3a's, but if not, and you cannot find a dimensioned drawing to work from, this image of NOS AR-3a grille frames may be of some use to you.

[xmas111]

Actually I can take one of my grills and give the exact measurements if you need them.

John

[Charles218]

I'm sorry for the delay in replying to this thread, I wasn't aware that it was seeing more activity. For some reason notifications do not work for me so I have to check in from time to time to get caught up.

After having the blanks cut at the lumber yard, my friend with the fancy equipment gave me a few verbal hints and left me to my own to finish the job. The most helpful suggestion was to build a frame out of 2 x 4's to hold the grille material steady while cutting. I'm attaching a couple of photos so you can see exactly what I came up with. I used one screw in each corner to hold it down, drilled a few holes as starting points for my saber saw and went at it. I gave up trying to make the cuts perfect, it was just too difficult, they are close enough and will be covered with the grille cloth. Or, am I missing something here, is there are reason, other then aesthetics, why I should get the cuts exact? I just didn't bother to go back and make the curves clean and smooth and some of the straight cuts are, well not absolutely straight.

I'm ready for the cloth and just discovered that I only have enough for three grilles and I need four. That puts me another couple of weeks before I finish. Then on to the next project, not sure which one of the many