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Topographic Model Bases - Frequently Asked Questions

 

  1. How long does a topographic site model take?
  2. What do you charge for your topographic models?
  3. What kind of foam do you use?
  4. Can I get a topographic model sample?
  5. Can you use other foams or other materials?
  6. We're a "full service" architectural model shop.  Could you keep our relationship secret?
  7. Do you make those "laser models" we've heard so much about?
  8. Will you finish our architectural model for us?
  9. What kind of paint can we use?
  10. How can we get an accurate estimate of cost and time to produce a site model?
  11. Is your shop fully  COMPUTERIZED?
  12. How can you help me show roads on a landscape model?
  13. How about showing paths?
  14. I haven't painted much foam.  Do you have any painting tips to offer?
  15. Is the dust hazardous to breathe?
  16. Is the foam flammable?
  17. What kind of glue can we use?
  18. How do you dimensionally compensate for the steps which you sand off?
  19. How easy is it to carve your foam?
  20. What contour interval do you recommend?
  21. Do you provide realistically smooth models, without steps?
  22. Do we need to provide perfect contour drawings?
  23. If we only have five foot contours and we want a model with 1' contours, do we have to draw them?
  24. How can you help us with building installation?
  25. Should we exaggerate the vertical scale?
  26. How can we show  project phases or options? 
  27. How can we make revisions to our model?
  28. How do you produce very deep models?
  29. Do the laminations show on very deep models?
  30. What dimensional constraints should we keep in mind?
  31. I'm a designer who needs a landform model. What do you recommend?
  32. Can you help us show property lines?
  33. Can you help us smooth out those jagged lines the computer used to simplify curved landforms?
  34. What do you do with "messy" contours?
  35. Our drawing shows existing terrain. Can you do some "cut and fill"  so the road doesn't look so silly?
  36. Doesn't such dense foam make it hard to "plant" trees?
  37. Can we stop by and see your machine?
  38. Do you recommend the architectural model companies you've listed?
  39. What payment terms can we arrange?
  40. What kind of discounts do you give?
  41. Our drawing is a cut, spliced and revised. mess.  Do we need to redraw it or highlight the contours with a red pencil?

1.  How long does a topographic model take?

We produce most models in a week or less and ship them by overnight or two-day express.  Small models can often be produced in a day or two.  Large, multi-section models are likely to take more than a week. With three large machines available, we can generally adapt to most any schedule. 

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2.  What do you charge for your models?

Our charge is based on the time and materials, which are determined mainly by two factors:  the overall, bounding-rectangular, volume of the model (not the "net" volume) and the complexity of the model shape.  Once you know the size and contour "step" you require, the following guidelines should help provide a preliminary  "order of magnitude" estimate:  

Please don't hesitate to contact us for more guidance and help in your planning.

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3.  What kind of foam do you use?

Our standard foam is 8 lb/cf polyurethane, custom "foamed" by the manufacturer.  We believe this density and special foaming procedure provides for the best model appearance, with a good balance between durability and weight.  The higher density is especially important if you're not planning on special model protection or on casting a reinforced copy.  The polyurethane formula is ideal for a variety of finish techniques, unlike expanded polystyrene foam.  Please note that the natural color of the foam varies due to the chemistry of foaming.  This foam color will generally vary within a model and also change slightly when exposed to ultraviolet light.  [Lighter foams cost less but look coarser and require more protection.]  If you want more uniform and predictable color, we recommend that the foam be painted.

Our computerized machinery has made it possible to use a wider range of materials, including dense foams and acrylic (pretty much any machinable material which does not require coolant).  Particularly appealing to some designers is our 18 lb/cf foam, which will provide a model which looks almost like it's cut from a solid block of greenish-grey chipboard.

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4.  Can I get a topographic model sample?

Just phone, write, or e-mail, being sure to include your name and address.  No charge if ordinary US Postal Service delivery is acceptable.   If you are in a rush, with your account number, we'll FedEx a sample "overnight."  Our samples are generally 8lb/cf except by special request.

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5.  Can you use other foams or other materials?

We will work with most any material which can be cut well by CNC router and which does not require coolant.  This includes any urethane foam, some other plastic foams, acrylic, wood,  even bronze. Most of our models are cut from urethane foam because it is lighter, easier to handle and easier to finish in a variety of ways.  Please refer to our companion venture www.Vermont-carving.com for a look at our new and expanding line of wood models.

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6.  We're a large "full service" architectural model shop.  Could you keep our relationship secret?

Certainly - this is not unusual.  You might be surprised, however, how easily your clients would appreciate the value of specialization these days.  This is especially true with almost everyone using fax, e-mail and overnight delivery services.  A lot of architectural model builders find that they don't use their "foam carving machine" often enough, and they are delighted to be able to reclaim the space and keep their shop much cleaner.  [Very few people require that their home or office be constructed by a "full service" builder.  Just think of us as "the bulldozer guys."]

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7.  see FAQcomputer.htm


8.  Will you finish our architectural model for us?

We used to say we only painted one general color.  This has been changed by new technology.  We now offer a new and unique method we call "Machined Masking.".  This means that we will "finish cut" one portion of a model  (most often the road pattern) and paint it a color of your choice prior to finish cutting the remainder of the model.  When our router cuts the remainder of the model, it will remove unwanted paint and only leave paint in the designated areas.  At this stage the  model may  be suitable as a "study model" with contours cut, roads painted, buildings excavated and sidewalks "engraved" or "scored."  This is especially true if the material you select a foam color which does not need to be painted (perhaps our gray 18 lb/cf foam  or our brown 15 lb/cf foam).  Some clients may prefer to add a final general "misting" or "wash" to modify the overall color, without hiding the road color entirely.  If we apply this general tint, then we also have the option of cutting certain areas away to remove the raw foam - as to show a fine pattern of paths.

.machined masking for complex color

Since we are specialists "to the trade,"  we provide an "unfinished" product which generally requires additional work.     The nature of this additional work can only be determined by someone who knows the overall needs of the project - including the purpose of the model and the way in which it is to be displayed and viewed .  People who do not normally fabricate models would probably be wise to involve or at least consult a full service model maker.

Upon special request, we sometimes mount our foam models on a rigid substrate, such as MDF.  While this may be a convenient low-cost alternative for the handling of a foam model, it should not be viewed as a permanent display base.    Except for small models, we recommend an  additional structural frame to support an MDF-based model and to stabilize it against bowing or bending.  This frame might include an outer rail for mechanical protection and as a means to support an acrylic cover.    Even models which are properly mounted and framed should not be crated in a way which allows them to be inverted and dropped during shipment, because this could fracture the bonds between model and base, causing serious damage.

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9.  What kind of paint can we use?

Any paint.  No ordinary coating will damage the foam and we've heard good reports on all kinds of paint.  The only warnings we've heard pertain to models which people coated with relatively thick coatings of epoxy or urethane.  It seems that coating shrinkage can cause cracking (and even warp a model).

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10.  How can we get an accurate estimate of cost and time to produce a model?

If your data can be communicated with a .dwg or .dxf, the best first step would probably be to send a copy, along with a description of the model you desire, to nk@landfoam.com.  If the file is over 2MB, please call to discuss using our ftp site.

For manually produced models, the ideal would be to send us a set of drawings at the scale of the model.  If schedule or convenience requires, however, we can work with sketches and/or description, by voice, fax or e-mail.  The key information is the plan dimensions, the scale, the step required, the amount of relief, and some description of the complexity.  You can reach us by:

voice:         1 802 728 7098
fax:             1 802 728 7099

mail:         Landfoam North
               #6341 VT Rte. 12A
                Braintree, VT
                USA

e-mail:    nk@landfoam.com

Please note that now that we have two shops to serve you, the computerized models are likely to be fabricated at our Somerville, Massachusetts shop - Landfoam Models Inc. (LMI).  The handmade models and some of the computer fabricated models will be produced by Landfoam North, in Vermont.

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11.  please see our "FAQcomputer.htm"

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12.  please see our "road illustration"

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13.  please see our "road illustration"

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14.  please see our "painting tips"s

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15.   Is the dust hazardous to breathe?

We haven't found anything to indicate that the dust is more hazardous than ordinary environmental and shop dust, which should be avoided.  

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16.  Is the foam flammable?

 It is produced with a fire retardant ingredient.  This reduces the hazard to a low level for most model  installations.  Certain applications, such as a large foam model which is wall-mounted in a public space, should be studied carefully to determine if the surface coating provides additional protection from ignition.

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17.  What kind of glue can we use? 

First, no ordinary glue will damage the foam itself.  Since the foam is "closed cell," it would be hard to predict the speed with which air-drying adhesives will solidify.  Due also to the general need for "gap filling," capability we most often recommend two-part liquid epoxy, selected so that you have enough working time.  Contact adhesives are also acceptable under some circumstances, but you may need an extra coat on the foam side, and you should avoid joining rigid components unless they have large contact areas (without forced bending).  [An obvious warning is to avoid letting an adhesive get on a surface which is to be exposed - unless it doesn't matter that the texture is changed by cell filling.]

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18.  How do you dimensionally compensate for the steps which you sand off?

This pertains to handmade models.  First, we  produce sanded models with very fine contour intervals (except at steep sections) in order to minimize "stair stepping" and reduce sanding.  Second, we mill the large flat areas one step lower than the drawing shows - in order to compensate for the fact that they will not be sanded down   Our computerized models are cut according to a virtual model surface which is created and sometimes "sculpted" by computer prior to cutting..

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19.  How easy is it to carve your foam?

 The 8lb/cf  foam is easy to cut with ordinary woodworking and carving tools, including your Exacto #11.  It's also good to sand.   Denser foams get progressively more difficult to make large cuts.

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20.  What contour interval do you recommend?

This would depend mostly on the purpose of the model, on the scale, and on the amount of relief across the model.   If the relief is less than 2" (50 mm) or a detailed building model will be installed, you are likely to prefer fine contour, maybe .020" - .040" (0.5 - 1.0 mm).  If the model is deeper than three inches, or if it's just for "massing" study, contours of .60" - .10" may be acceptable.  In selecting a contour interval, keep in mind the following general tendencies:

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21.  Do you provide realistically smooth models, without steps?

Yes.  We produce these in two alternative ways:  by  CNC router - or  by milling a stepped model and then sanding it smooth.   The determining factor is often the quality of the contour data.  If it is good, the relief can be milled to a smooth surface and then line information can be engraved over the undulating surface, according to a 2D vector file.  For example, paths, roads and property lines could be engraved with a cutting tool of  .016 diameter, to a depth of  .01" .  If you are preparing a 3D model for machining (as by STL file), please note that it is generally best to leave as many discontinuities (especially building excavations and road curbs) out of the virtual model.  Please provide continuous lines to define such discontinuities.  We would "drape" this information over the virtual model  and cut the defined areas as specified.

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22.  Do we need to provide perfect contour drawings?

No.  We certainly recommend checking the drawings to avoid serious errors, omissions and ambiguities.  We produce a "shop drawing" prior to milling.  This helps us work out problems with our clients, often with the help of faxed inquiries and clarifications. For computerized models, it is generally necessary for the client to provide drawings which are suitable, because we do not have the staff required to edit and refine your drawings quickly enough to meet most schedules.

Requirements for computer-cut models vary according to whether you want smooth or stepped finish.  In either case, we can work with several surface formats which you might provide.

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23.  If we only have five foot contours and we want a model with 1' contours, do we have to draw them?

This is one advantage of manually guided machinery.  It facilitates addition of interpolated contours.  It would be good, however, if you check for special conditions, such as entries and terraces, where you may want to provide spot elevations to guide interpolation.  Addition of interpolated contours is a more complex issue for computer produced models, so we would need to study the individual situations.

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24.  How can you help us with building installation?

 We provide  "rough excavations" to whatever depth you request.  We generally recommend cutting to the "lowest adjacent grade" and leaving a little foam "trim margin."   When good CAD data allows, our CNC router produced models can be cut with accurate building footprints, or with a setback which you specify.  The corners of the footprints will be radiused due to our round cutting tool but can be "squared out" with chisel or blade.

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25.  Should we exaggerate the vertical scale? 

It depends on the terrain adn the scale.   In some cases, it's helpful to help people understand the shapes.  It can produce confusion, however, especially relative to truly scaled buildings and trees.  The larger the scale of the model, the less likely you are to need exaggeration.   For instance,in some cases,  a model at 1:5,000 metric scale might well be exaggerated 200% but a model of 1"=20' is generally better to produce at true scale.

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26.  How can we show  project phases or options? 

If you can define the area of special interest, we can provide interchangeable inserts.  If you must study the model first, you can ship it back to us and have us cut a hole and fit it with one or more inserts.

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27.  How can we make revisions to our model?

The models can be carved or sanded.  Although we can provide limited quantities of thinly cut foam so that you can make small laminated additions, we would only recommend it in very unusual circumstances.  If significant "bulldozer work" is required you might consider using the foam as a substrate, upon which you model with clay.  Alternatively, you could return the model (by prior arrangement) and have us cut one or more "inserts."

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28.  How do you produce very deep models? 

We build them up from layers of  three and four inch thick foam.  This reduces material cost, reduces tool-clearance problems, and avoids warpage due to the internal stresses that are often present in blocks of foam.  Furthermore, we don't know of a manufacturer which routinely provides foam blocks to the maximum size of our models. We conceal our glue by "inlaying" or "pocketing" each upper layer in the layer below it.

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29.  Do the laminations show on very deep models?

Yes, but they can be quite inconspicuous.   On  stepped models, we put the lamination at a step.  On smooth models, we use our CNC router to cut a "pocket" into which we "inlay" the upper layer.  This inlaid lamination eliminates the "feathered glue joint" which used to be impractical to avoid on most deep handmade models.


30.  What dimensional constraints should we keep in mind?

We only stock material which is 48" x 96", so that is a good size to remember.  When appropriate, however, our new Thermwood can cut individual sections up to 60" by 120," .   Our largest model to date was about 18' by 24' and our deepest model about 36" deep.  Single pieces in excess of 48" x 96" (which are not glued together) require additional time for special order materials.

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31.  I'm a designer who needs a landform model.  What do you recommend? 

If you need a fine finished model, we recommend that you contact a model maker who can provide a fully coordinated product. Ideally, this would involve one of our landform bases.   If you only need a simple site model, or a study model, we'd be delighted to provide one directly to you.  If you like, this could include colored roads and engraved paths, with a handsome choice of background foam color.

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13.  How about showing paths?

If the data is in good digital format, we our CNC router gives us the most options for showing paths.  Most simply, path lines can be delineated by "engraving" or "scoring" with a fine cutting tool, perhaps 1/64" diameter.   This outlining may delineate the paths well enough or it will be a big help in locating the paths so that you can paint them with a fine brush or mask and spray them.

If the paths are outlined with a good continuous polyline, we can "depress" them very slightly as we often depress roads.  This method also gives us the option of differentiating the paths with color.  If you like, we can either depress the paths very slightly so as to reveal the natural foam color after painting is finished, or we can add an additional color tint so that roads paths and land all have a different color. 

If the scale is large enough, such as 1/20" = 1' or larger, we can treat the paths as small "roads" and depress them whether or not we use our CNC router.  The manual method does not allow for detailed painting. 

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32.  Can you help us show property lines?

In the case of models we cut by computerized router, we can "drape" vector data from a separate 2D file which you provide.   This allows us to"engrave" ("score") such information with an appropriate cutting tool.  For handmade models, we can mark important corners with a "pencil twirl" (or a push pin) in the foam.  You would have to connect the dots. 

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33.  Can you smooth out these jagged lines that computers used to simplify curving landforms.

We can perform some "smoothing" without any problem.  Completely eliminating that "style" may increase our labor charge, depending on the extent of revision necessary.  

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34.  What do you do with "messy" contours?  

When the complexity is clearly irrelevant to the use of the model (and only adds "visual noise") we try to reduce it a reasonable amount.    We don't get involved in much of this editing when we are producing computerized models, unless specifically requested and planned.

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35.  Our drawing shows existing terrain, can you do some "cut and fill" so the road doesn't look so silly?

When specifically requested, we try to roughly balance cut and fill in a way to keep grades to realistic limits - such as 5% for parking and 10% for roads.  Note that such contours would be approximated - only intended for better conceptual illustration, done without detailed analysis.    This is generally more practical for manually cut models than for computerized models.

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36.  Doesn't such dense foam make it hard to "plant" trees?

Although you can't simply push fine "weed" trees into the foam, it's pretty simple to push a wire of the proper diameter into the foam, in order to prepare a hole.

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37.  Can we stop by and see your machine?

Certainly.  Just schedule your visit by calling in advance, please.

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38.  Do you recommend the companies you've listed?

As suppliers, we are not in a position to know or to judge such intangibles as reliability, economy and cooperation.  We can only see the end result - and let that speak for itself.  For that reason we do not want to be held responsible for the future performance of any company but our own.   If we learn that our landform isn't well used for the intended purpose (from quick study model to fine museum exhibit), we'll avoid promoting the offender.

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39.  What payment terms can we arrange?

For the first model, we require a 50% retainer and the balance COD.  After that we can gradually relax the terms toward 33% retainer and the balance in thirty days.  

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40.  What kind of discounts do you give?

With our "repeat" customers, we discount our charges according to the volume of business they give us.


41.  Our drawing is a cut, spliced and revised mess.  Do we need to redraw it or highlight the contours with a red pencil?

Generally not.  Although we certainly prefer good computerized data or an easy-to-read print, we often prepare a "shop drawing" from information which is not well digitized.  At this stage we can usually figure out the intent of the drawing - and, if necessary, telephone, fax or e-mail our questions for your clarification.  The important thing is for you to be sure that your plan is not misleading enough to cause us to make the wrong assumptions and interpretations.  Only you know the purpose of the model, so only you can judge the degree of control which is appropriate to exercise over the details of the landform.  Unfortunately, there's no denying that bad drawings can cause problems which we might not be able to avoid.   Our manually guided machinery is generally the best option for cutting models from "challenging" drawings.


Welcome Page               Top of FAQ                 Landform Specialist

Landfoam Topographics

voice: 1 802 728 7098
fax: 1 802 728 7099
email: nk @ landfoam.com

#6341  VT Rte. 12A
Braintree, VT  05060
 USA

 


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Copyright © 2005-2007.  Landfoam Topographics.  All rights reserved.
Disclaimer:  This material is offered to provide helpful general guidelines based on available information.  We cannot be held responsible for the results of any misinterpretation or misapplication of this material.
Revised: April 15, 2008.


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